A181494 - OEIS

A181494

Twin primes (A001097) of the form 3*2^k +- 1.

5, 7, 11, 13, 191, 193, 786431, 786433

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OFFSET

1,1

LINKS

FORMULA

A181494(n) = A181493(ceiling(n/2)) + (-1)^n = A007283(A181490(ceiling(n/2))) + (-1)^n.

PROG

(PARI) for( k=1, 999, ispseudoprime(3<<k-1)|next; ispseudoprime(3<<k+1)|next; print1(3<<k-1, ", ", 3<<k+1, ", "))

CROSSREFS

KEYWORD

more,nonn

AUTHOR

M. F. Hasler, Oct 30 2010

STATUS

approved