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 A211389 #17 Jun 27 2025 00:45:25
%S A211389 3,5,9,14,16,26,54,67,74,103,161,293,236,432,249,788,1078,796,1885,
%T A211389 2091,1712,2618,4099,7088,8137,8091,16086,12595,27627,22835,44576,
%U A211389 31305,68888,109617,86463,77206,126383,202035
%N A211389 a(n) is the first occurrence of n in sequence A209266.
%e A211389 A209266 = {0, 0, 1, 1, 2, 2, 2, 1, 3, 3, 1, 3, 3, 4, 3, 5, 4, 2, 5, 4, 4, 4, 4, 3, 3, 6, 6, 4,...}.
%e A211389 Number 1 first appears as A209266(3), number 2 as A209266(5), number 3 as A209266(9)...
%e A211389 So, a = {3, 5, 9, ...} starting from a(1)=3.
%t A211389 aim = 32; a = Table[0, {i, 1, aim}]; zeros = aim; i = 2; While[i++; p = Prime[i]; ct = 0; Do[If[(PrimeQ[p - j]) && (PrimeQ[p + j]), f = Last[FactorInteger[j]][[1]]; If[f <= 5, ct++]], {j, 2, p, 2}]; If[(ct <= aim) && (a[[ct]] == 0), a[[ct]] = i; zeros--]; zeros > 0]; a
%Y A211389 Cf. A209266.
%K A211389 nonn,hard,more
%O A211389 1,1
%A A211389 _Lei Zhou_, Feb 07 2013