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A073181 Sum of divisors of n which are not greater than the squarefree kernel of n. 4
1, 3, 4, 3, 6, 12, 8, 3, 4, 18, 12, 16, 14, 24, 24, 3, 18, 12, 20, 22, 32, 36, 24, 16, 6, 42, 4, 28, 30, 72, 32, 3, 48, 54, 48, 16, 38, 60, 56, 30, 42, 96, 44, 40, 33, 72, 48, 16, 8, 18, 72, 46, 54, 12, 72, 36, 80, 90, 60, 108, 62, 96, 41, 3, 84, 144, 68, 58, 96, 144, 72, 16, 74 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

a(n) >= A048250(n).

LINKS

Antti Karttunen, Table of n, a(n) for n = 1..10000

EXAMPLE

The squarefree kernel of 56 = 7 * 2^3 is 14 = 7*2 and the divisors <= 14 of 56 are {1, 2, 4, 7, 8, 14}, therefore a(56) = 1 + 2 + 4 + 7 + 8 + 14 = 36.

PROG

(PARI)

A007947(n) = factorback(factorint(n)[, 1]); \\ This function from Andrew Lelechenko

A073181(n) = sumdiv(n, d, d*(d<=A007947(n))); \\ Antti Karttunen, Sep 10 2017, after Michel Marcus's code for A073183.

CROSSREFS

Cf. A000203, A007947, A073180, A073183.

Sequence in context: A238162 A048250 A323363 * A183100 A046897 A109506

Adjacent sequences:  A073178 A073179 A073180 * A073182 A073183 A073184

KEYWORD

nonn,look

AUTHOR

Reinhard Zumkeller, Jul 19 2002

STATUS

approved

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Last modified February 24 00:38 EST 2020. Contains 332195 sequences. (Running on oeis4.)