login
A259047
Composite numbers which divide the concatenation of their prime factors, with multiplicity, in ascending order.
10
28749, 21757820799, 4373079629403
OFFSET
1,1
COMMENTS
a(2) found by Jens Kruse Andersen, who also cleverly derived 119 large terms of the sequence from the factorization of numbers of the form 10^k+1 (see Links).
10^13 < a(4) <= 7810053011863508278028459 (the smallest of J. K. Andersen's large terms).
EXAMPLE
4373079629403 is equal to 3*367*2713*1464031 and it is a divisor of 336727131464031, hence it is in the sequence.
CROSSREFS
Cf. A248915.
Sequence in context: A213460 A043660 A296814 * A237321 A249957 A157610
KEYWORD
nonn,more,base,hard,bref
AUTHOR
Giovanni Resta, Jun 17 2015
STATUS
approved