A055657 If a(n) is prime, a(n+1) = a(n) followed by a 1; if a(n) is composite, a(n+1) = concatenation of distinct prime factors of a(n).

0, 1, 11, 111, 337, 3371, 33711, 317661, 3195573, 33134361, 313849599, 3714945219, 3412771691, 7487538813, 38359316903, 1311540119013, 3837735218627, 38377352186271, 371907319435931, 715238131259661, 3907388967590269, 72910334611861889, 729103346118618891

Offset

0,3

Comments

Is the sequence eventually cyclic? - Charles R Greathouse IV, Apr 27 2010

Links

Sean A. Irvine, Table of n, a(n) for n = 0..91

Maple

a:= proc(n) option remember; `if`(n=0, 0, (t-> parse(cat(`if`(isprime(t)
      or t<2, [t, 1][], sort([numtheory[factorset](t)[]])[]))))(a(n-1)))
    end:
seq(a(n), n=0..30);  # Alois P. Heinz, Apr 03 2022

Crossrefs

Cf. A049121.

Sequence in context: A336523 A209233 A062095 * A049121 A143573 A248039

Adjacent sequences: A055654 A055655 A055656 * A055658 A055659 A055660

Keyword

nonn,base

Author

Harvey P. Dale, Jun 08 2000

Status

approved