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 A063449 #27 Mar 08 2025 06:00:35 %S A063449 11,17,19,23,29,31,35,41,43,47,53,59,67,71,79,83,89,95,97,101,103,107, %T A063449 109,111,113,119,125,127,131,137,139,143,149,151,155,159,161,163,167, %U A063449 169,173,179,181,191,197,199,203,209,211,215,219,223,227,229,233,239 %N A063449 Numbers k for which d(k+1) > 2*d(k), where d(j) = A000005(j). %C A063449 d(p+1) >= 2d(p) holds for all primes p and for some composite integers, as well. %H A063449 Amiram Eldar, <a href="/A063449/b063449.txt">Table of n, a(n) for n = 1..10000</a> (terms 1..1000 from Harry J. Smith) %e A063449 For k = 29: 2*d(29) = 2*2 = 4 < 8 = d(30). %e A063449 For k = 95: 2*d(95) = 2*4 = 8 < 12 = d(96). %t A063449 Position[Partition[DivisorSigma[0,Range[250]],2,1],_?(2#[[1]]<#[[2]]&),1,Heads->False]//Flatten (* _Harvey P. Dale_, Nov 16 2020 *) %o A063449 (PARI) is(m) = numdiv(m + 1) > 2*numdiv(m); \\ _Harry J. Smith_, Aug 21 2009 %Y A063449 Cf. A000005, A063446, A063450. %K A063449 nonn %O A063449 1,1 %A A063449 _Labos Elemer_, Jul 24 2001 %E A063449 Edited by _Jon E. Schoenfield_, Sep 05 2017