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 A188629 #25 Apr 17 2024 02:32:49 %S A188629 2,4,8,14,16,22,38,58,135,158,178,256,297,382,502,542,568,676,718,878, %T A188629 1202,1215,1312,1318,1382,1438,1593,1622,1822,2018,2144,2336,2558, %U A188629 2578,2744,2858,2902,3062,3118,3296,3375,3778,3993,4023,4064,4192,4282 %N A188629 Numbers k such that k^2 has one more divisor than k^2 - 1. %H A188629 Amiram Eldar, <a href="/A188629/b188629.txt">Table of n, a(n) for n = 1..10000</a> %p A188629 isA188629 := proc(n) if numtheory[tau](n^2) = numtheory[tau](n^2-1)+1 then true; else false; end if; end proc: %p A188629 for n from 1 do if isA188629(n) then print(n) ; end if; end do: # _R. J. Mathar_, Apr 14 2011 %t A188629 Select[Range[10000], DivisorSigma[0, #^2 - 1] + 1 == DivisorSigma[0, #^2] &] %o A188629 (PARI) is(k) = k > 1 && numdiv(k^2-1) + 1 == numdiv(k^2); \\ _Amiram Eldar_, Apr 17 2024 %Y A188629 Cf. A000005, A000290, A055927, A172438. %K A188629 nonn %O A188629 1,1 %A A188629 _Juri-Stepan Gerasimov_, Apr 06 2011