A117836 Semiprimes of the form floor(e^k).

403, 3269017, 485165195, 3584912846, 26489122129, 29048849665247, 639843493530054949, 114200738981568428366295718, 66631762164108958342448140502408732626873, 492345828601205839975486205911330449483779

Offset

1,1

Links

Giovanni Resta, Table of n, a(n) for n = 1..17

Formula

a(n) = {floor(e^k) = p*q for integer k, p and q prime}. a(n) = A000149 INTERSECTION A001358.

Example

a(1) = 403 = floor(e^6) = 13 * 31.
a(2) = 3269017 = floor(e^15) = 773 * 4229.
a(3) = 485165195 = floor(e^20) = 5 * 97033039.
a(4) = 3584912846 = floor(e^22) = 2 * 1792456423.
a(5) = 26489122129 = floor(e^24) = 103 * 257175943.

Crossrefs

Cf. A000040, A000149, A001358, A074496.

Sequence in context: A165808 A283662 A097741 * A185640 A185637 A234675

Adjacent sequences: A117833 A117834 A117835 * A117837 A117838 A117839

Keyword

nonn

Author

Jonathan Vos Post, Apr 30 2006

Extensions

a(6)-a(10) from Giovanni Resta, Jun 15 2016

Status

approved