A074130 Group successively larger prime numbers so that the sum of the n-th group is a multiple of n. Sequence gives the number of prime in each group.

1, 2, 2, 4, 2, 2, 9, 12, 23, 14, 2, 4, 29, 4, 10, 32, 10, 6, 18, 2, 21, 4, 32, 6, 25, 6, 29, 46, 64, 28, 17, 26, 2, 12, 52, 6, 21, 66, 195, 56, 112, 34, 34, 8, 66, 30, 27, 14, 130, 10, 95, 2, 82, 34, 63, 14, 40, 96, 101, 18, 61, 44, 39, 20, 39, 8, 3, 26, 46, 4, 26, 280, 82, 24, 32

Offset

1,2

Links

Table of n, a(n) for n=1..75.

Mathematica

NextPrime[n_] := Block[{k = n + 1}, While[ !PrimeQ[k], k++ ]; k]; a = {}; k = 1; Do[s = 0; c = 0; While[k = NextPrime[k]; s = s + k; !IntegerQ[s/n], c++ ]; a = Append[a, c+1], {n, 1, 75}]; a

Crossrefs

Cf. A000040, A074128, A074129, A074131.

Sequence in context: A320164 A113200 A113198 * A320163 A113334 A127796

Adjacent sequences: A074127 A074128 A074129 * A074131 A074132 A074133

Keyword

nonn

Author

Amarnath Murthy, Aug 27 2002

Extensions

(2), (3, 5), (7, 11), (13, 17, 19, 23), (29, 31), (37, 41), (43, 47, 53, 59, 61, 67, 71, 73, 79), (83, 89, 97, 101, 103, 107, 109, 113, 127, 131, 137, 139), (149, 151, 157, 163, 167, 173, 179, 181, 191, 193, 197, ..., 269), ...

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

Status

approved