OFFSET
1,2
FORMULA
a(n) = A051801(n^2). - Michel Marcus, Mar 07 2022
EXAMPLE
a(32) = 8 because 32*32 = 1024 and 1*2*4 = 8.
MATHEMATICA
Table[Times@@(IntegerDigits[n^2]/.(0->1)), {n, 120}] (* Harvey P. Dale, Dec 12 2017 *)
PROG
(PARI) a(n) = {digs = digits(n^2); prod(i=1, #digs, if (digs[i], digs[i], 1)); } \\ Michel Marcus, Aug 12 2013
(PARI) a(n) = vecprod(select(x->(x>1), digits(n^2))); \\ Michel Marcus, Mar 07 2022
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Nels Olson, Oct 19 2012
STATUS
approved