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 A219841 #6 Nov 29 2012 13:18:18 %S A219841 1,4,9,17,29,44,62,86,108,139,166,204,245,282,331,371,427,472,535,602, %T A219841 656,730,788,869,953,1021,1113,1184,1283,1359,1465,1575,1660,1777, %U A219841 1866,1990,2118,2216,2351,2453,2595,2702,2851,3004,3120,3280,3400,3567,3738 %N A219841 Positions of numbers 2^n + 3^n (n >= 0) in A004050. %H A219841 Zak Seidov, <a href="/A219841/b219841.txt">Table of n, a(n) for n = 0..1000</a> %e A219841 a(0) = 1 because 2^0 + 3^0 = 1 = A004050(1), %e A219841 a(1) = 4 because 2^1 + 3^1 = 5 = A004050(4). %Y A219841 Cf. A004050. %K A219841 nonn %O A219841 0,2 %A A219841 _Zak Seidov_, Nov 29 2012