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A166686 Numbers m such that m plus the sum of the indices of the prime factors of the m-th composite (counted with multiplicity) is prime. 0
1, 2, 8, 9, 13, 14, 16, 17, 30, 31, 33, 34, 53, 59, 61, 65, 80, 85, 89, 92, 94, 96, 97, 103, 113, 116, 117, 121, 127, 128, 142, 143, 160, 163, 180, 182, 188, 189, 206, 208, 216, 221, 227, 235, 236, 242, 255, 256, 261, 262, 265, 271, 294, 297, 298, 300, 304, 315 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..58.

EXAMPLE

1st composite = 4 = 2*2 = (1st prime)*(1st prime) and 1+1+1=3 (prime), so 1 is in the sequence.

2nd composite = 6 = 2*3 = (1st prime)*(2nd prime) and 2+1+2=5 (prime), so 2 is in the sequence.

CROSSREFS

Cf. A000040, A002808.

Sequence in context: A081381 A235524 A239133 * A064833 A073606 A047353

Adjacent sequences:  A166683 A166684 A166685 * A166687 A166688 A166689

KEYWORD

nonn

AUTHOR

Juri-Stepan Gerasimov, Oct 18 2009

EXTENSIONS

6 removed, 49 removed, 94 inserted, 102 removed, 103 inserted by R. J. Mathar, Oct 28 2009

Definition reworded by Jon E. Schoenfield, Apr 15 2014

STATUS

approved

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Last modified December 4 15:24 EST 2016. Contains 278750 sequences.