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 A073687 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 first term in each group. 2
 4, 12, 16, 24, 56, 58, 65, 68, 70, 77, 87, 94, 99, 102, 106, 114, 116, 118, 140, 142, 185, 195, 219, 221, 224, 226, 235, 255, 259, 266, 278, 280, 290, 302, 310, 318, 334, 366, 370, 375, 377, 399, 403, 411, 413, 415, 442, 447, 462, 494, 530, 532, 550, 568, 575 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Table of n, a(n) for n=1..55. MATHEMATICA t1 = Rest[Select[Range[580], ! PrimeQ[#] &]]; t = {}; s = c = 0; Do[s += i; c += 1; If[PrimeQ[s], AppendTo[t, t1[[Flatten[Position[t1, i]] - c + 1]]]; s = c = 0], {i, t1}]; Flatten[t] (* Jayanta Basu, Jul 07 2013 *) CROSSREFS Cf. A073685, A073686. Sequence in context: A261958 A057962 A186303 * A187084 A090818 A075191 Adjacent sequences: A073684 A073685 A073686 * A073688 A073689 A073690 KEYWORD nonn AUTHOR Amarnath Murthy, Aug 11 2002 EXTENSIONS More terms from Lior Manor Aug 13 2002 STATUS approved

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Last modified December 6 09:02 EST 2023. Contains 367600 sequences. (Running on oeis4.)