OFFSET
0,1
COMMENTS
a(20) <= 733333326; a(34) <= 666666666666; a(39) <= 4888888888884 and a(44) <= 7333333333326. - Farideh Firoozbakht, Dec 10 2006
EXAMPLE
a(0)=13 since 13 is the smallest number that cannot be represented as a product of two palindromes. a(5)=484 since 484= 1*484 = 2*242 = 4*121 = 22*22 = 11*44.
MATHEMATICA
f[n_]:=f[n]=Length[Select[Divisors[n], #<=n^(1/2)&&FromDigits[ Reverse[IntegerDigits[ # ]]]==#&&FromDigits[Reverse[IntegerDigits [n/# ]]]==n/#&]]; a[n_]:=(For[m=1, f[m] != n, m++ ]; m); Do[Print[a[n]], {n, 0, 18}] - Farideh Firoozbakht, Dec 10 2006
CROSSREFS
KEYWORD
base,nonn
AUTHOR
Giovanni Resta, Apr 02 2006
EXTENSIONS
More terms from Farideh Firoozbakht, Dec 10 2006
a(19)-a(27) from Donovan Johnson, Aug 04 2009
STATUS
approved