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A283597 Numbers n such that both 6n+1 and 6n+7 are semiprimes. 1
8, 14, 19, 41, 42, 43, 48, 49, 59, 74, 84, 85, 88, 92, 93, 97, 108, 113, 116, 132, 139, 144, 148, 149, 157, 158, 159, 162, 163, 189, 190, 193, 198, 209, 210, 211, 222, 223, 224, 225, 226, 227, 231, 234, 235, 250, 251, 259, 264, 272, 280, 285, 306, 307, 315, 316, 317, 318, 319, 320, 323, 326, 327, 340, 345, 349, 358, 361, 368, 376, 386, 387, 388 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Both n and n+1 are terms in A112775.

LINKS

Table of n, a(n) for n=1..73.

MATHEMATICA

po[x_]=PrimeOmega[x]; Select[Range[500], po[6# + 1] == po[6# + 7] == 2 &]

PROG

(PARI) for(n=1, 388, if(bigomega(6*n + 1) == 2 && bigomega(6*n + 7) == 2, print1(n, ", "))) \\ Indranil Ghosh, Mar 15 2017

CROSSREFS

Cf. A112771 (6n+1 semiprimes), A112775 (6n+1 is semiprime), A001358 (semiprimes).

Sequence in context: A096229 A231718 A212020 * A112277 A078754 A068638

Adjacent sequences:  A283594 A283595 A283596 * A283598 A283599 A283600

KEYWORD

nonn

AUTHOR

Zak Seidov, Mar 14 2017

STATUS

approved

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Last modified May 26 15:29 EDT 2019. Contains 323597 sequences. (Running on oeis4.)