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A115209 a(0)=1. a(n) = number of earlier terms of the sequence which when added to n produce a composite number. 4
1, 0, 0, 1, 2, 2, 4, 4, 8, 4, 8, 5, 9, 8, 12, 7, 13, 12, 14, 12, 19, 16, 17, 17, 18, 17, 22, 20, 23, 17, 21, 24, 29, 25, 29, 25, 25, 29, 31, 28, 33, 32, 27, 34, 34, 34, 36, 37, 40, 36, 39, 41, 43, 43, 38, 42, 47, 47, 46, 44, 45, 48, 49, 48, 51, 49, 49, 49, 59, 54, 58, 55, 54, 59 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,5

LINKS

Diana Mecum, Table of n, a(n) for n = 0..200

EXAMPLE

Adding 6 to the first 6 terms (terms 0 through 5) of the sequence gives [7,6,6,7,8,8]. Of these terms, four are composite, so a(6) = 4.

MATHEMATICA

a = {1}; For[n = 1, n < 90, n++, in = 0; For[j = 1, j < Length[a] + 1, j++, If[ ! PrimeQ[n + a[[j]]], in++ ]]; AppendTo[a, in]]; a (* Stefan Steinerberger, Jun 03 2007 *)

CROSSREFS

Cf. A115207, A115208, A115210.

Sequence in context: A005852 A274625 A292253 * A139210 A300123 A175359

Adjacent sequences:  A115206 A115207 A115208 * A115210 A115211 A115212

KEYWORD

nonn

AUTHOR

Leroy Quet, Jan 16 2006

EXTENSIONS

More terms from Stefan Steinerberger and Diana L. Mecum, Jun 03 2007

STATUS

approved

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Last modified September 20 14:44 EDT 2021. Contains 347586 sequences. (Running on oeis4.)