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

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

Crossrefs

Cf. A001065, A008578, A027751.

Sequence in context: A294888 A364858 A001065 * A324535 A318501 A318325

Adjacent sequences: A173452 A173453 A173454 * A173456 A173457 A173458

Keyword

nonn

Author

Omar E. Pol, Nov 22 2010

Status

approved