A074121 Group successively larger composite numbers so that the sum of the n-th group is a multiple of n. Sequence gives the first term in each group.

4, 6, 8, 12, 14, 18, 20, 24, 25, 36, 48, 52, 69, 104, 112, 129, 160, 187, 207, 243, 259, 291, 301, 310, 315, 333, 356, 361, 388, 425, 450, 471, 519, 528, 608, 633, 665, 668, 687, 721, 783, 790, 875, 897, 994, 1016, 1047, 1138, 1174, 1179, 1274, 1278, 1344

Offset

1,1

Links

Table of n, a(n) for n=1..53.

Mathematica

NextComposite[n_] := Block[{k = n + 1}, While[PrimeQ[k], k++ ]; k]; a = {}; k = 1; Do[s = 0; a = Append[a, NextComposite[k]]; While[k = NextComposite[k]; s = s + k; ! IntegerQ[s/n], ], {n, 1, 55}]; a

Crossrefs

Cf. A002808, A074129, A074120, A074122, A074123.

Sequence in context: A028876 A271346 A053579 * A175088 A275671 A370745

Adjacent sequences: A074118 A074119 A074120 * A074122 A074123 A074124

Keyword

nonn

Author

Amarnath Murthy, Aug 27 2002

Extensions

Edited, corrected and extended by Robert G. Wilson v, Aug 29 2002

Status

approved