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 A305719 #17 Nov 24 2024 21:01:49 %S A305719 1,2,3,11,22,26,39,41,68,75,97,101,109,111,119,121,129,131,139,141, %T A305719 202,208,212,218,222,225,235,246,254,256,264,303,307,313,319,321,329, %U A305719 331,339,341,349,351,359,361,369,371,379,381,389,391,399,401,409,411,419,421,429,431,439,441,638 %N A305719 Numbers whose squares have the same first and last digits. %e A305719 For k = 11, k^2 = 121; %e A305719 for k = 26, k^2 = 676. %t A305719 Select[Range[638], (d = IntegerDigits[#^2]; d[[1]] == d[[-1]]) &] (* _Giovanni Resta_, Jun 25 2018 *) %o A305719 (PARI) for(n=1, 10^3, my(d=digits(n^2)); if( d[1]==d[#d], print1(n,", "))); \\ _Joerg Arndt_, Jun 10 2018 %o A305719 (Python) %o A305719 def ok(n): s = str(n*n); return s[0] == s[-1] %o A305719 print(list(filter(ok, range(1, 639)))) # _Michael S. Branicky_, Jul 16 2021 %Y A305719 Cf. A227858, A116499, A116501. %Y A305719 Cf. A123912, A186438. %K A305719 nonn,base,easy %O A305719 1,2 %A A305719 _Neville Holmes_, Jun 08 2018