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 A115441 #5 Jun 18 2021 18:16:41 %S A115441 465,536,718,822,3428,6573,90907,980202,3636361,6363640,41176468, %T A115441 58823533,413533838,426573430,428571426,432620009,567379992,571428575, %U A115441 573426571,586466163,686261111,725274729,727272725,731321308 %N A115441 Numbers whose square is the concatenation of two numbers k and k+9. %e A115441 82640_82649 = 90907^2. %Y A115441 Cf. A030467, A106497, A115430, A115427, A115438, A115439, A115440, A115442, A115443, A115444, A115445, A115446, A115447. %K A115441 base,nonn %O A115441 1,1 %A A115441 _Giovanni Resta_, Jan 24 2006