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A162194 Sum of divisors of nonprime number A018252(n). 3
1, 7, 12, 15, 13, 18, 28, 24, 24, 31, 39, 42, 32, 36, 60, 31, 42, 40, 56, 72, 63, 48, 54, 48, 91, 60, 56, 90, 96, 84, 78, 72, 124, 57, 93, 72, 98, 120, 72, 120, 80, 90, 168, 96, 104, 127, 84, 144, 126, 96, 144, 195, 114, 124, 140, 96, 168, 186, 121, 126, 224, 108, 132 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Also, 1 together with the numbers A073255.

LINKS

Harvey P. Dale, Table of n, a(n) for n = 1..1000

FORMULA

a(n) = A000203(A018252(n)).

MAPLE

with(NumberTheory): seq(`if`(isprime(n), NULL, sigma(n)), n = 1 .. 100); # Reza K Ghazi, Aug 28 2021

MATHEMATICA

Join[{1}, DivisorSigma[1, #]&/@Select[Range[100], CompositeQ]] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, May 27 2017 *)

PROG

(PARI) a = List(); for(n=1, 100, if(!isprime(n), listput(a, sigma(n)))); Vec(a) \\ Reza K Ghazi, Aug 28 2021

(SageMath) [sigma(n) for n in range(1, 101) if not is_prime(n)] # Reza K Ghazi Aug 28 2021

CROSSREFS

Cf. A000203, A018252, A073255, A162194, A162195.

Sequence in context: A351474 A349854 A073255 * A247954 A145310 A177988

Adjacent sequences:  A162191 A162192 A162193 * A162195 A162196 A162197

KEYWORD

easy,nonn

AUTHOR

Omar E. Pol, Jul 04 2009

STATUS

approved

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Last modified July 4 08:01 EDT 2022. Contains 355070 sequences. (Running on oeis4.)