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A060278 Sum of composite divisors of n less than n. 7
0, 0, 0, 0, 0, 0, 0, 4, 0, 0, 0, 10, 0, 0, 0, 12, 0, 15, 0, 14, 0, 0, 0, 30, 0, 0, 9, 18, 0, 31, 0, 28, 0, 0, 0, 49, 0, 0, 0, 42, 0, 41, 0, 26, 24, 0, 0, 70, 0, 35, 0, 30, 0, 60, 0, 54, 0, 0, 0, 97, 0, 0, 30, 60, 0, 61, 0, 38, 0, 59, 0, 117, 0, 0, 40, 42, 0, 71, 0, 98, 36, 0, 0, 127, 0, 0, 0 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,8

COMMENTS

From Reinhard Zumkeller, Apr 05 2013: (Start)

a(n) = Sum_{k=2..A000005(n)-1} A010051(A027751(n,k));

a(A037143(n)) = 0;

a(A033942(n)) > 0. (End)

LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

MAPLE

for n from 1 to 300 do s := 0: for j from 2 to n-1 do if isprime(j) then else if n mod j = 0 then s := s+j fi; fi: od: printf(`%d, `, s) od:

MATHEMATICA

Join[{0}, Table[Total[Select[Most[Rest[Divisors[n]]], !PrimeQ[#]&]], {n, 2, 90}]] (* Harvey P. Dale, Oct 25 2011 *)

PROG

(Haskell)

a060278 1 = 0

a060278 n = sum $ filter ((== 0) . a010051) $ tail $ a027751_row n

-- Reinhard Zumkeller, Apr 05 2013

(PARI) a(n) = sumdiv(n, d, if ((d<n) && (d>1) && !isprime(d), d)); \\ Michel Marcus, Jan 13 2020

CROSSREFS

Cf. A000203, A035322, A035321, A023891.

Sequence in context: A105570 A327054 A101419 * A046770 A046782 A074037

Adjacent sequences:  A060275 A060276 A060277 * A060279 A060280 A060281

KEYWORD

nonn,easy

AUTHOR

Jack Brennen, Mar 28 2001

EXTENSIONS

More terms from James A. Sellers and Matthew Conroy, Mar 29 2001

STATUS

approved

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Last modified July 11 17:57 EDT 2020. Contains 335632 sequences. (Running on oeis4.)