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 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. 4

%I

%S 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,

%T 64,28,17,26,2,12,52,6,21,66,195,56,112,34,34,8,66,30,27,14,130,10,95,

%U 2,82,34,63,14,40,96,101,18,61,44,39,20,39,8,3,26,46,4,26,280,82,24,32

%N 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.

%t 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

%Y Cf. A000040, A074128, A074129, A074131.

%K nonn

%O 1,2

%A _Amarnath Murthy_, Aug 27 2002

%E (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), ...

%E Edited, corrected and extended by _Robert G. Wilson v_, Aug 29 2002

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Last modified January 18 17:05 EST 2022. Contains 350455 sequences. (Running on oeis4.)