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 A077510 #15 May 25 2025 22:58:39 %S A077510 2,3,7,9,12,13,21,28,32,36,45,52,55,57,61,65,70,76,79,81,84,86,89,101, %T A077510 104,110,119,121,131,135,139,145,147,155,160,162,172,181,185,187,195, %U A077510 205,216,222,223,228,231,253,258,262,273,278,286,288,292,297,305,310 %N A077510 Numbers k such that k + pi(k) is a prime. %C A077510 Conjecture: for k > 5, prime(n) <= k < prime(n+1) <= k + pi(k), i.e., the smallest prime greater than k is <= k + pi(k). Equality holds for k = 7. %H A077510 Charles R Greathouse IV, <a href="/A077510/b077510.txt">Table of n, a(n) for n = 1..10000</a> %e A077510 21 is a member as 21 + pi(21) = 21 + 8 = 29 is a prime. %t A077510 Select[Range[350],PrimeQ[#+PrimePi[#]]&] (* _Harvey P. Dale_, Nov 19 2011 *) %o A077510 (PARI) for(n=1,200,if(isprime(n+primepi(n)),print1(n,", "))) \\ _Derek Orr_, Jun 22 2015 %o A077510 (PARI) pi=0; p=2; forprime(q=3,1e3, pi++; for(n=p,q-1, if(isprime(n+pi), print1(n", "))); p=q) \\ _Charles R Greathouse IV_, Jun 23 2015 %Y A077510 Cf. A000040, A000720, A061067, A076757. %K A077510 nonn %O A077510 1,1 %A A077510 _Amarnath Murthy_, Nov 08 2002 %E A077510 More terms from _David Garber_, Nov 10 2002