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 A257292 #29 Nov 22 2023 21:15:01
%S A257292 5,9,11,13,15,19,21,23,25,27,29,31,33,35,37,39,43,45,47,49,51,53,55,
%T A257292 57,59,61,63,65,67,69,71,73,75,77,79,81,83,85,87,89,91,93,95,97,101,
%U A257292 103,105,107,109,111,113,115,117,119,121,123,125,127,129,131
%N A257292 Numbers whose square can be written as the sum of two consecutive nonsquares.
%C A257292 Equivalently, odd numbers such that neither of the two integers next to n^2/2 is a square.
%C A257292 Complement of A257282 = square roots of A256944.
%C A257292 The odd numbers missing here are 1, 3, 7, 17, 41, 99, ... = A078057 (see also A001333 = abs(A123335)).
%H A257292 Michael De Vlieger, <a href="/A257292/b257292.txt">Table of n, a(n) for n = 1..10000</a>
%e A257292 9 is a term because 9^2 = 81 = 40 + 41, neither of which are square.
%t A257292 Select[Range[1, 131, 2], AllTrue[{Floor[#^2/2], Ceiling[#^2/2]}, ! IntegerQ@ Sqrt@ # &] &] (* _Michael De Vlieger_, Dec 11 2015 *)
%o A257292 (PARI) select( is(n)={bittest(n,0) && !issquare(n^2\2) && !issquare(n^2\/2)}, [0..140]) \\ Corrected Jul 06 2021, thanks to an observation by _Bill McEachen_
%Y A257292 Cf. A001333, A078057, A123335, A256944, A257282.
%K A257292 nonn
%O A257292 1,1
%A A257292 _M. F. Hasler_, May 08 2015