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A156541 Multiplicative closure of Sophie Germain primes (A005384). 5
1, 2, 3, 4, 5, 6, 8, 9, 10, 11, 12, 15, 16, 18, 20, 22, 23, 24, 25, 27, 29, 30, 32, 33, 36, 40, 41, 44, 45, 46, 48, 50, 53, 54, 55, 58, 60, 64, 66, 69, 72, 75, 80, 81, 82, 83, 87, 88, 89, 90, 92, 96, 99, 100, 106, 108, 110, 113, 115, 116, 120, 121, 123, 125, 128, 131, 132 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

A156542(a(n)) = A001221(a(n));

Subsequence of A130176.

LINKS

R. Zumkeller, Table of n, a(n) for n = 1..1000

MATHEMATICA

Select[Range@132, And @@ PrimeQ[FactorInteger[#][[All, 1]]*2 + 1] &] (* Ivan Neretin, Aug 30 2015 *)

CROSSREFS

Cf. A156541, A156543.

Sequence in context: A230780 A067942 A130176 * A277620 A031143 A055492

Adjacent sequences:  A156538 A156539 A156540 * A156542 A156543 A156544

KEYWORD

nonn

AUTHOR

Reinhard Zumkeller, Feb 10 2009

STATUS

approved

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Last modified December 4 02:25 EST 2016. Contains 278745 sequences.