number-theory / Distribution of prime gaps

Erdős and Prachar's question: do the increases of pn/np_n/n have positive lower density?

Theorem 1.1: for every fixed C>0C>0 there are c(C)>0c(C)>0 and N0(C)N_0(C) with #{n≤N:pn+1−pn>Clog⁡pn}≥c(C)N\#\{n\le N:p_{n+1}-p_n>C\log p_n\}\ge c(C)N for all N≥N0N\ge N_0, with ordinary lower density and equal weight on prime indices. Corollary 1.2 (take C=2C=2) answers Erdős-Prachar: the increases of pn/np_n/n have positive lower density. The main theorem is stronger than the posed question. The constant c(C)c(C) is not made explicit or compared with the Poisson prediction e−Ce^{-C}, and the further questions recorded with Problem #968 on un<un+1<un+2u_n<u_{n+1}<u_{n+2} and un>un+1>un+2u_n>u_{n+1}>u_{n+2} are not addressed.

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number-theorySep 25, 2026Significance 15/100Registry: lean checked

Erdős and Prachar's question: do the increases of pn/np_n/n have positive lower density?

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Theorem 1.1: for every fixed C>0C>0 there are c(C)>0c(C)>0 and N0(C)N_0(C) with #{n≤N:pn+1−pn>Clog⁡pn}≥c(C)N\#\{n\le N:p_{n+1}-p_n>C\log p_n\}\ge c(C)N for all N≥N0N\ge N_0, with ordinary lower density and equal weight on prime indices. Corollary 1.2 (take C=2C=2) answers Erdős-Prachar: the increases of pn/np_n/n have positive lower density. The main theorem is stronger than the posed question. The constant c(C)c(C) is not made explicit or compared with th…

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Theorem 1.1: for every fixed C>0C>0 there are c(C)>0c(C)>0 and N0(C)N_0(C) with #{n≤N:pn+1−pn>Clog⁡pn}≥c(C)N\#\{n\le N:p_{n+1}-p_n>C\log p_n\}\ge c(C)N for all N≥N0N\ge N_0, with ordinary lower density and equal weight on prime indices. Corollary 1.2 (take C=2C=2) answers Erdős-Prachar: the increases of pn/np_n/n have positive lower density. The main theorem is stronger than the posed question. The constant c(C)c(C) is not made explicit or compared with the Poisson prediction e−Ce^{-C}, and the further questions recorded with Problem #968 on un<un+1<un+2u_n<u_{n+1}<u_{n+2} and un>un+1>un+2u_n>u_{n+1}>u_{n+2} are not addressed.

Theorem 1.1: for every fixed C>0C>0 there are c(C)>0c(C)>0 and N0(C)N_0(C) with #{n≤N:pn+1−pn>Clog⁡pn}≥c(C)N\#\{n\le N:p_{n+1}-p_n>C\log p_n\}\ge c(C)N for all N≥N0N\ge N_0, with ordinary lower density and equal weight on prime indices. Corollary 1.2 (take C=2C=2) answers Erdős-Prachar: the increases of pn/np_n/n have positive lower density. The main theorem is stronger than the posed question. The constant c(C)c(C) is not made explicit or compared with the Poisson prediction e−Ce^{-C}, and the further questions recorded with Problem #968 on un<un+1<un+2u_n<u_{n+1}<u_{n+2} and un>un+1>un+2u_n>u_{n+1}>u_{n+2} are not addressed.

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Erdős and Prachar's question: do the increases of $p_n/n$ have positive lower density? — Mathematical Frontier Network