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 A073221 #10 Apr 09 2025 19:42:19 %S A073221 1,9,17,145,153,289,2457,2465,2601,4913,41761,41769,41905,44217,83521, %T A073221 709929,709937,710073,712385,751689,1419857,12068785,12068793, %U A073221 12068929,12071241,12110545,12778713,24137569,205169337,205169345,205169481,205171793,205211097,205879265,217238121,410338673 %N A073221 The terms of A073213 (sums of two powers of 17) divided by 2. %F A073221 (17^n + 17^m) / 2, n = 0, 1, 2, 3 ..., m = 0, 1, 2, 3, ... n. %e A073221 a(4) = 145 = (17^2+17^0) / 2. %Y A073221 Cf. A073213. %K A073221 nonn,easy,tabl %O A073221 0,2 %A A073221 _Jeremy Gardiner_, Jul 21 2002 %E A073221 Offset corrected by _Alois P. Heinz_, Jul 27 2021