cp's OEIS Frontend

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.

A336357 Numbers k such that sigma(k) has fewer distinct prime factors than k.

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%I A336357 #22 Aug 07 2021 15:00:05
%S A336357 21,30,42,66,70,84,93,102,105,110,138,154,156,165,170,186,210,217,230,
%T A336357 231,238,255,273,282,310,318,322,330,336,345,357,364,372,374,381,385,
%U A336357 390,399,400,420,426,434,462,465,470,483,506,510,525,530,546,561,570,595,630,642,651,658,660,682,690,705,710,714
%N A336357 Numbers k such that sigma(k) has fewer distinct prime factors than k.
%C A336357 Numbers k for which A058062(k) < A001221(k).
%C A336357 If terms x and y are present and gcd(x,y) = 1, then x*y is present also.
%t A336357 Select[Range[800],PrimeNu[#]>PrimeNu[DivisorSigma[1,#]]&] (* _Harvey P. Dale_, Aug 07 2021 *)
%Y A336357 Cf. A336355 (characteristic function), A336358 (complement).
%Y A336357 Cf. also A055743, A336359.
%K A336357 nonn
%O A336357 1,1
%A A336357 _Antti Karttunen_, Jul 20 2020