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 A074122 Group successively larger composite numbers so that the sum of the n-th group is a multiple of n. Sequence gives the number of terms in the n-th group. 3
 1, 1, 3, 1, 3, 1, 3, 1, 9, 8, 4, 13, 27, 6, 15, 25, 22, 16, 29, 14, 26, 9, 8, 3, 16, 19, 4, 23, 31, 20, 17, 42, 7, 68, 21, 26, 3, 16, 30, 53, 6, 73, 18, 84, 19, 26, 77, 32, 5, 83, 3, 55, 16, 107, 1, 44, 5, 40, 7, 207, 17, 41, 17, 14, 23, 49, 100, 46, 34, 36, 47, 216, 50, 17, 7, 58 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS a(n) = 1 for n: 1,2,4,6,8,55,154,616,(10^4). LINKS 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; c = 0; While[k = NextComposite[k]; s = s + k; !IntegerQ[s/n], c++ ]; a = Append[a, c + 1], {n, 1, 80}]; a CROSSREFS Cf. A002808, A074130, A074120, A074121, A074123. Sequence in context: A070039 A227991 A319137 * A335182 A319992 A255894 Adjacent sequences:  A074119 A074120 A074121 * A074123 A074124 A074125 KEYWORD nonn AUTHOR Amarnath Murthy, Aug 27 2002 EXTENSIONS Edited, corrected and extended by Robert G. Wilson v, Aug 29 2002 STATUS approved

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Last modified August 5 05:22 EDT 2020. Contains 336209 sequences. (Running on oeis4.)