1,1

Table of n, a(n) for n=1..13.

Hisanori Mishima, Factorizations of many number sequences

Factorization of Bernoulli and Euler numbers

a(1) = 20 so the numerator of Bernoulli(20) = 174611 = 283 * 617 is a semiprime.

Cf. A092132.

Sequence in context: A117737 A062908 A111323 * A114843 A174629 A221651

Adjacent sequences: A250286 A250287 A250288 * A250290 A250291 A250292

nonn

Eric Chen, Dec 24 2014

approved