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.
%I A337275 #16 Oct 21 2020 17:57:32 %S A337275 -1,3,10,6,14,18,22,23,26,51,46,54,58,87,99,106,107,110,114,134,135, %T A337275 142,155,171,182,195,199,215,210,214,255,259,271,274,295,299,315,323, %U A337275 326,347,367,371,390,391,394,398,443,451,471,475,478,491,495,511,523,531,543,547,567,575,579,599,627 %N A337275 Index of appearance of 2*prime(n) in A336957, or -1 if 2*prime(n) never appears. %C A337275 It is a strong conjecture that 2*prime(n) appears in A336957 for all n>1, and it is known that 4 does not appear. %C A337275 See also the comment in A336957 discussing when primes first appear in A336957. %H A337275 N. J. A. Sloane, <a href="/A337275/b337275.txt">Table of n, a(n) for n = 1..20000</a> %H A337275 N. J. A. Sloane, <a href="/A337275/a337275.txt">Table comparing the present sequence and A338074</a> %e A337275 A336957(14) = 22 = 2*prime(5), so a(5) = 14. %Y A337275 Cf. A336957, A337276, A338074. %K A337275 sign %O A337275 1,2 %A A337275 _N. J. A. Sloane_, Sep 09 2020