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 A116283 #9 Aug 01 2021 03:05:48 %S A116283 7,30,64,42753,57241,75423,425072,574922,979528,4301393,5698601, %T A116283 7028666,4925000747,5074999247,7748266574,8511881484,8814851184, %U A116283 7059602159672,7106167933828,7439286611621,7485852385777 %N A116283 k times k+7 gives the concatenation of two numbers m and m-1. %o A116283 (Python) %o A116283 def ok(n): %o A116283 s = str(n*(n+7)); h = (len(s)+1)//2; return int(s[:h])-1 == int(s[h:]) %o A116283 print(list(filter(ok, range(2, 10**6)))) # _Michael S. Branicky_, Jul 30 2021 %Y A116283 Cf. A001704, A028563. %Y A116283 Cf. A116152, A116269, A116282, A116284, A116291. %K A116283 nonn,base %O A116283 1,1 %A A116283 _Giovanni Resta_, Feb 06 2006