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 A073220 #7 Nov 21 2013 12:47:51 %S A073220 1,7,13,85,91,169,1099,1105,1183,2197,14281,14287,14365,15379,28561, %T A073220 185647,185653,185731,186745,199927,371293,2413405,2413411,2413489, %U A073220 2414503,2427685,2599051,4826809,31374259,31374265,31374343,31375357 %N A073220 Terms of A072390 (sums of two powers of 13) divided by 2. %F A073220 (13^n + 13^m) / 2, n = 0, 1, 2, 3 ..., m = 0, 1, 2, 3, ... n. %e A073220 a(4) = 85 = (11^2+11^0) / 2 %t A073220 Union[Total/@Tuples[13^Range[0,9],2]]/2 (* _Harvey P. Dale_, Sep 15 2011 *) %Y A073220 Cf. A072390. %K A073220 easy,nonn %O A073220 1,2 %A A073220 _Jeremy Gardiner_, Jul 21 2002