OFFSET
1,1
COMMENTS
A subsequence of A000217.
Up to 10^12, only 4 terms admit two representations, namely 3081, 22791, 410871 and 1675365. - Giovanni Resta, Jul 19 2015
LINKS
Giovanni Resta, Table of n, a(n) for n = 1..509 (terms < 10^12)
EXAMPLE
a(1) = 3 = 1*1 + 1 + 1.
a(2) = 15 = 3*3 + 3 + 3.
a(3) = 21 = 10*1 + 10 + 1.
a(4) = 91 = 45*1 + 45 + 1.
a(5) = 120 = 10*10 + 10 + 10.
a(6) = 153 = 6*21 + 6 + 21.
CROSSREFS
KEYWORD
nonn
AUTHOR
Alex Ratushnyak, Jul 04 2015
STATUS
approved