OFFSET
1,1
EXAMPLE
n = 6: a(6) = 83089 because 131197531 = 1579 * 83089.
MATHEMATICA
s=1; ss={}; Do[news=FromDigits[Flatten[{IntegerDigits[n], IntegerDigits[s]}]]; fi=FactorInteger[news][[ -1, 1]]; s=news; AppendTo[ss, fi], {n, 3, 60, 2}]; A109840=ss
With[{nn=17}, Table[FactorInteger[FromDigits[Flatten[IntegerDigits/@Reverse[Range[1, 2n+1, 2]]]]][[-1, 1]], {n, nn}]] (* Harvey P. Dale, Sep 02 2023 *)
CROSSREFS
KEYWORD
base,nonn
AUTHOR
Zak Seidov, Jul 05 2005
STATUS
approved