A073685 Group the composite numbers so that the sum of each group is a prime: (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, 52, 54, 55), ...; sequence gives number of terms in each group.

5, 3, 5, 25, 2, 5, 2, 2, 5, 8, 6, 4, 2, 3, 5, 2, 2, 18, 2, 35, 8, 21, 2, 2, 2, 6, 17, 3, 6, 9, 2, 8, 11, 7, 5, 15, 27, 3, 4, 2, 18, 3, 7, 2, 2, 22, 4, 12, 27, 31, 2, 16, 16, 5, 2, 16, 2, 21, 7, 12, 2, 2, 4, 22, 8, 10, 2, 7, 2, 2, 8, 7, 8, 2, 4, 22, 2, 30, 8, 21, 2, 3, 28, 24, 4, 10, 7, 4, 6, 3, 2

Offset

1,1

Links

Table of n, a(n) for n=1..91.

Mathematica

t1 = Rest[Select[Range[970], ! PrimeQ[#] &]]; t = {}; s = c = 0; Do[s += i; c += 1; If[PrimeQ[s], AppendTo[t, c]; s = c = 0], {i, t1}]; t (* Jayanta Basu, Jul 07 2013 *)

Crossrefs

Cf. A073686, A073687.

Sequence in context: A144386 A256787 A265782 * A019212 A201928 A021655

Adjacent sequences: A073682 A073683 A073684 * A073686 A073687 A073688

Keyword

nonn

Author

Amarnath Murthy, Aug 11 2002

Extensions

More terms from Lior Manor Aug 13 2002

Status

approved