cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A164574 Numbers k such that k and k+6 are both prime powers.

This page as a plain text file.
%I A164574 #16 Oct 01 2020 04:05:21
%S A164574 1,2,3,5,7,11,13,17,19,23,25,31,37,41,43,47,53,61,67,73,83,97,101,103,
%T A164574 107,121,125,131,151,157,163,167,173,191,193,223,227,233,251,257,263,
%U A164574 271,277,283,307,311,331,337,343,347,353,361,367,373,383,433,443,457
%N A164574 Numbers k such that k and k+6 are both prime powers.
%C A164574 Numbers n such that n + (0, 6) is a prime power pair.
%C A164574 n + (0, 2m), m >= 1, being an admissible pattern for prime pairs, since (0, 2m) = (0, 0) (mod 2), has high density.
%C A164574 n + (0, 2m-1), m >= 1, being a non-admissible pattern for prime pairs, since (0, 2m-1) = (0, 1) (mod 2), has low density [the only possible pairs are (2^a - 2m-1, 2^a) or (2^a, 2^a + 2m-1), a >= 0.]
%H A164574 Amiram Eldar, <a href="/A164574/b164574.txt">Table of n, a(n) for n = 1..10000</a> (terms 1..2492 from  Daniel Forgues)
%t A164574 Join[{1},Select[Range[500],AllTrue[{#,#+6},PrimePowerQ]&]] (* The program uses the AllTrue function from Mathematica version 10 *) (* _Harvey P. Dale_, Sep 30 2018 *)
%o A164574 (PARI) is(n)=if(n<4,return(n>0)); isprimepower(n) && isprimepower(n+6) \\ _Charles R Greathouse IV_, Apr 24 2015
%Y A164574 Cf. A023201, A000961.
%Y A164574 k and (x) are prime powers: A006549 (k+1) A120431 (k+2), A164571 (k+3), A164572 (k+4), A164573 (k+5), this sequence (k+6).
%K A164574 nonn
%O A164574 1,2
%A A164574 _Daniel Forgues_, Aug 16 2009
%E A164574 Edited by _Daniel Forgues_, Aug 17 2009