id:A013919 - OEIS Search Results

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Numbers n such that sum of first n composites is composite.

+0
5

1, 2, 3, 4, 6, 7, 8, 9, 10, 11, 12, 13, 15, 16, 18, 19, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 38, 39, 40, 41, 42, 44, 45, 46, 49, 50, 51, 52, 55, 56, 57, 58, 59, 60, 61, 62, 65, 66, 67, 69, 70, 71, 72, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 87, 88, 89, 90, 91, 92, 93 (list; graph; listen)

	OFFSET	`1,2`
	MATHEMATICA	`f[ n_Integer ] := Block[ {k = n + PrimePi[ n ] + 1}, While[ k - PrimePi[ k ] - 1 != n, k++ ]; k ]; s = 0; Do[ s = s + f[ n ]; If[ ! PrimeQ[ s ], Print[ n ] ], {n, 1, 100} ]`
	CROSSREFS	`Cf. A013920, A013921.` `Sequence in context: A052413 A003247 A076216 this_sequence A101771 A035058 A004776` `Adjacent sequences: A013916 A013917 A013918 this_sequence A013920 A013921 A013922`
	KEYWORD	`nonn`
	AUTHOR	`njas, Henri Lifchitz (100637.64(AT)CompuServe.COM)`
	EXTENSIONS	`More terms from David W. Wilson (davidwwilson(AT)comcast.net)`

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Last modified July 4 18:25 EDT 2008. Contains 140886 sequences.

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