A162194 - OEIS

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A162194

Sum of divisors of nonprime number A018252(n).

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