1,1

Eric Weisstein's World of Mathematics, Pierpont Prime

Eric Weisstein's World of Mathematics, Almost Prime

a(n) is in this sequence iff there exist nonnegative integers K and L such that Omega((2^K)*(3^L)+1) = 3.

a(1) = 28 = (2^0)*(3^3)+1 = 2 * 2 * 7.

a(2) = 244 = (2^0)*(3^5)+1 = 2 * 2 * 61.

a(3) = 325 = (2^2)*(3^4)+1 = 5 * 5 * 13.

a(4) = 385 = (2^7)*(3^1)+1 = 5 * 7 * 11.

a(11) = 7777 = (2^5)*(3^5)+1 = 7 * 11 * 101.

a(115) = 94143178828 = (2^0)*(3^23)+1 = 2 * 2 * 23535794707.

a(119) = 137438953473 = (2^37)*(3^0)+1 = 3 * 1777 * 25781083.

a(196) = 281474976710657 = (2^48)*(3^0)+1 = 193 * 65537 * 22253377.

Intersection of A014612 and A055600.

A005109 gives the Pierpont primes, which are primes of the form (2^K)*(3^L)+1.

A113432 gives the Pierpont semiprimes, 2-almost primes of the form (2^K)*(3^L)+1.

A111344 gives the Pierpont 4-almost primes, of the form (2^K)*(3^L)+1.

A111345 gives the Pierpont 5-almost primes, of the form (2^K)*(3^L)+1.

A111346 gives the Pierpont 6-almost primes, of the form (2^K)*(3^L)+1.

A113739 gives the Pierpont 7-almost primes, of the form (2^K)*(3^L)+1.

A113740 gives the Pierpont 8-almost primes, of the form (2^K)*(3^L)+1.

A113741 gives the Pierpont 9-almost primes, of the form (2^K)*(3^L)+1.

Adjacent sequences: A112794 A112795 A112796 this_sequence A112798 A112799 A112800

Sequence in context: A138405 A024015 A119544 this_sequence A085438 A092341 A042522

easy,nonn

Jonathan Vos Post (jvospost2(AT)yahoo.com), Nov 08 2005

Extended by Ray Chandler (rayjchandler(AT)sbcglobal.net), Nov 08 2005