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A281599 Numbers k such that A000005(k) = A000005(A000041(k)). 3

%I #22 Feb 26 2020 17:18:02

%S 1,2,3,5,8,13,42,56,65,87,93,95,102,108,114,123,143,146,157,161,190,

%T 195,198,200,203,210,218,234,235,238,266,275,287,312,321,370,375,380,

%U 385,410,416,437,475,491,513,568,572,582,590,626,627,636,660,685,702

%N Numbers k such that A000005(k) = A000005(A000041(k)).

%C Numbers k such that the number of divisors of k is equal to the number of divisors of the number of partitions of k.

%H Charles R Greathouse IV and Amiram Eldar, <a href="/A281599/b281599.txt">Table of n, a(n) for n = 1..500</a> (terms 1..225 from Charles R Greathouse IV)

%t Select[Range[1500], DivisorSigma[0, #] == DivisorSigma[0, PartitionsP[#]] &] (* _Indranil Ghosh_, Mar 09 2017 *)

%o (PARI) select(n->numdiv(n)==numdiv(numbpart(n)), vector(750, n, n))

%Y Cf. A000005, A000041, A281597, A281598.

%K nonn

%O 1,2

%A _Colin Barker_, Jan 25 2017

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Last modified July 23 18:13 EDT 2024. Contains 374553 sequences. (Running on oeis4.)