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A173455 Row sums of triangle A027751. 2
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 (list; graph; refs; listen; history; text; internal format)
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: A069250 A294888 A001065 * A324535 A318501 A318325

Adjacent sequences:  A173452 A173453 A173454 * A173456 A173457 A173458

KEYWORD

nonn

AUTHOR

Omar E. Pol, Nov 22 2010

STATUS

approved

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Last modified October 14 07:00 EDT 2019. Contains 327995 sequences. (Running on oeis4.)