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 A133952 #23 Jul 12 2025 08:36:25
%S A133952 1,0,1,4,10,19,43,77,137,243,497,749,1520,2518,3952,5294,10628,14564,
%T A133952 29199,40855,60605,95786,191700,242580,339732,531896,677048,916946,
%U A133952 1834106,2332346,4664982,5528982,7863685,12164443,16422235,19594843
%N A133952 a(n) = the number of "isolated divisors" of n!. A positive divisor, k, of n is isolated if neither (k-1) nor (k+1) divides n.
%H A133952 Chai Wah Wu, <a href="/A133952/b133952.txt">Table of n, a(n) for n = 1..60</a> (terms 1..50 from Ray Chandler)
%F A133952 a(n) = A027423(n) - A133951(n) = A132881(A000142(n)).
%p A133952 A133952 := proc(n) local divs,k,i,a ; divs := sort(convert(numtheory[divisors](n!), list)) ; a := 0 ; for i from 1 to nops(divs) do k := op(i,divs) ; if not k-1 in divs and not k+1 in divs then a := a+1 ; fi ; od: RETURN(a) ; end: for n from 1 do printf("%d,",A133952(n)) ; od: # _R. J. Mathar_, Oct 19 2007
%Y A133952 Cf. A133951, A027423.
%Y A133952 Cf. A000142, A132881.
%K A133952 nonn
%O A133952 1,4
%A A133952 _Leroy Quet_, Sep 30 2007
%E A133952 Corrected and extended by _R. J. Mathar_, Oct 19 2007
%E A133952 a(26)-a(35) from _Ray Chandler_, May 28 2008
%E A133952 a(36)-a(50) from _Ray Chandler_, Jun 20 2008