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A074120
Group successively larger composite numbers so that the sum of the n-th group is a multiple of n. Sequence gives the sum of the terms in the n-th group.
3
4, 6, 27, 12, 45, 18, 63, 24, 270, 330, 198, 780, 2314, 644, 1800, 3600, 3808, 3150, 6479, 3500, 7140, 2662, 2438, 936, 5175, 6526, 1431, 8596, 12586, 8730, 7812, 20768, 3663, 38488, 13020, 16848, 1998, 10830, 21099, 39840, 4715, 60732, 15953
OFFSET
1,1
EXAMPLE
(4), (6), (8, 9, 10), (12), (14, 15, 16), (18), (20, 21, 22), (24), (25, 26, 27, 28, 30, 32, 33, 34, 35), (36, 38, 39, 40, 42, 44, 45, 46), (48, 49, 50, 51), ...
MATHEMATICA
NextComposite[n_] := Block[{k = n + 1}, While[PrimeQ[k], k++ ]; k]; a = {}; k = 1; Do[s = 0; While[k = NextComposite[k]; s = s + k; !IntegerQ[s/n], ]; a = Append[a, s], {n, 1, 45}]; a
CROSSREFS
KEYWORD
nonn
AUTHOR
Amarnath Murthy, Aug 27 2002
EXTENSIONS
Edited, corrected and extended by Robert G. Wilson v, Aug 29 2002
STATUS
approved