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 A037197 #38 Mar 07 2025 03:00:14
%S A037197 1,2,8,12,32,52,75,84,90,98,128,150,156,338,360,392,525,528,560,600,
%T A037197 722,867,912,972,1050,1352,1452,1456,1525,1734,1922,2064,2160,2340,
%U A037197 2400,2888,2890,3050,3120,3216,3698,3744,3872,4080,4144,4200,4500,4575
%N A037197 Numbers k such that tau(sigma(k)) = tau(k) where tau(k) is the number of divisors of k and sigma(k) their sum.
%H A037197 Amiram Eldar, <a href="/A037197/b037197.txt">Table of n, a(n) for n = 1..10000</a> (terms 1..1000 from Reinhard Zumkeller)
%F A037197 Solutions to A000005(x) = A062068(x) = A000005(A000203(x)).
%F A037197 Conjecture: for n > 10^6, a(n) < n^2. - _Benoit Cloitre_, Aug 24 2002
%e A037197 k = 75: divisors(75) = {1, 3, 5, 15, 25, 75}, divisors(sigma(75)) = divisors(124) = {1, 2, 4, 31, 62, 124}, both 75 and sigma(75) have 6 divisors, so 75 is a term.
%t A037197 Do[s=DivisorSigma[0, DivisorSigma[1, n]]; s0=DivisorSigma[0, n]; If[Greater[s0, s], Print[n]], {n, 1, 1000}]
%t A037197 Select[Range[4600],DivisorSigma[0,#]==DivisorSigma[0,DivisorSigma[1,#]]&] (* _Harvey P. Dale_, Feb 08 2025 *)
%o A037197 (PARI) is(n)=numdiv(sigma(n))==numdiv(n) \\ _Charles R Greathouse IV_, Feb 13 2013
%Y A037197 Cf. A000005, A000203, A062068, A073802, A073803, A073804.
%K A037197 nonn
%O A037197 1,2
%A A037197 _Naohiro Nomoto_
%E A037197 Offset corrected by _Reinhard Zumkeller_, Jun 18 2009
%E A037197 Name edited by _Michel Marcus_, Nov 12 2023