A114340 Largest palindromic divisor of n!! (double factorial = A006882(n)).

1, 2, 3, 8, 5, 8, 7, 8, 9, 8, 99, 9, 9009, 252, 9009, 252, 9009, 48384, 969969, 48384, 969969, 405504, 969969, 405504, 969969, 405504, 969969, 525525, 969969, 525525, 79833897, 525525, 133464331, 595595, 5273993725, 595595

Offset: 1

Author

Giovanni Resta, Feb 07 2006

Keywords

• base
• nonn

Examples

			a(16)=252 since 252 is the largest palindromic factor of 16!!= 10321920=252* 40960.
		

Crossrefs

Cf. A006882, A093030, A093888.

Programs

Mathematica

palQ[n_]:= n == FromDigits@Reverse@IntegerDigits@n; Array[Max[Select[Divisors[ #!! ], palQ]] &, 40]

Formula

a(n) = A093030(A006882(n)). - Michel Marcus, Oct 13 2022