A173455 - OEIS

A173455

Row sums of triangle A027751.

1, 1, 1, 3, 1, 6, 1, 7, 4, 8, 1, 16, 1, 10, 9, 15, 1, 21, 1, 22, 11, 14, 1, 36, 6, 16, 13, 28, 1, 42, 1, 31, 15, 20, 13, 55, 1, 22, 17, 50, 1, 54, 1, 40, 33, 26, 1, 76, 8, 43, 21, 46, 1, 66, 17, 64, 23, 32, 1, 108, 1, 34, 41, 63, 19, 78, 1, 58, 27, 74, 1, 123, 1, 40, 49, 64, 19, 90, 1, 106

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OFFSET

1,4

COMMENTS

Essentially the same as A001065, but with a(1)=1.

Note that if n is a noncomposite number then a(n)=1.

LINKS

Antti Karttunen, Table of n, a(n) for n = 1..4096

MATHEMATICA

Array[Boole[# == 1] + DivisorSigma[1, #] - # &, 80] (* Michael De Vlieger, Oct 30 2017 *)

PROG

(PARI) a(n) = if (n==1, 1, sigma(n) - n); \\ Michel Marcus, Oct 30 2017