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 A178951 #19 Apr 27 2023 15:09:01 %S A178951 49,61,86,96,121,122,123,124,214,215,216,256,257,258,259,260,275,325, %T A178951 355,356,357,412,518,519,545,546,547,588,589,771,772,773,774,775,776, %U A178951 777,778,779,780,827,833,840,904,905,906,982,983,984,1176,1177 %N A178951 Numbers k such that A178609(k-1) = A178609(k) = A178609(k+1). %C A178951 Where A178609(n) is a measure of the largest index distance which allows prime(n) to be written as the arithmetic mean of two primes at equal distance to prime(n). %F A178951 A178609(a(n)-1) = A178609(a(n)) = A178609(a(n)+1). %o A178951 (Sage) is_A178951 = lambda n: len(set([A178609(n-1), A178609(n), A178609(n+1)])) == 1 # _D. S. McNeil_, Jan 04 2011 %Y A178951 Cf. A178609. %K A178951 nonn %O A178951 1,1 %A A178951 _Juri-Stepan Gerasimov_, Dec 31 2010