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 A215614 #46 Jun 28 2025 00:59:46 %S A215614 4,5,32,49,149,1049 %N A215614 Numbers k that are not multiples of 10 and such that sum of digits of k^2 is 7. %C A215614 Except for the number 1, the terms of this sequence and numbers 10^k+1 (A062397) are the only numbers (up to trailing 0's) whose square has sum of digits less than 9. - _M. F. Hasler_, Sep 23 2014 %C A215614 Is this sequence finite? See also A384095 for a similar problem with digit sum 9. - _M. F. Hasler_, Jun 20 2025 %C A215614 a(7) > 10^15 if it exists. - _David A. Corneth_, Jun 21 2025 %C A215614 a(7) > 10^65 if it exists. - _Michael S. Branicky_, Jun 25 2025 %C A215614 a(7) > 10^700 if it exists. - _Max Alekseyev_, Jun 27 2025 %t A215614 Select[Range[1500],Mod[#,10]!=0&&Total[IntegerDigits[#^2]]==7&] (* _Harvey P. Dale_, Aug 21 2022 *) %o A215614 (PARI) for(n=1,9e9, n%10&&sumdigits(n^2)==7&&print1(n",")) \\ _M. F. Hasler_, Sep 23 2014 %Y A215614 Cf. A004159 (sum of digits of n^2). %Y A215614 Subsequence of A262711. %Y A215614 Cf. A384094 (similar for digit sum 9), A384095 (subset of "sporadic solutions"). %K A215614 nonn,base,more %O A215614 1,1 %A A215614 _Zak Seidov_, Aug 17 2012 %E A215614 Edited and unproven keywords fini,full removed by _Max Alekseyev_, Jun 20 2025