A184392 - OEIS

A184392

a(n) is the product of palindromic divisors of n.

1, 2, 3, 8, 5, 36, 7, 64, 27, 10, 11, 144, 1, 14, 15, 64, 1, 324, 1, 40, 21, 484, 1, 1152, 5, 2, 27, 56, 1, 180, 1, 64, 1089, 2, 35, 1296, 1, 2, 3, 320, 1, 252, 1, 85184, 135, 2, 1, 1152, 7, 10, 3, 8, 1, 324, 3025, 448, 3, 2, 1, 720, 1, 2, 189, 64, 5, 18974736, 1, 8, 3, 70, 1, 10368, 1, 2, 15, 8, 5929, 36, 1, 320, 27, 2, 1, 1008, 5, 2, 3, 59969536, 1, 1620, 7, 8, 3, 2, 5, 1152, 1, 14, 970299, 40

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,2

LINKS

Indranil Ghosh, Table of n, a(n) for n = 1..10000

FORMULA

a(n) = A007955(n) / A179937(n).

EXAMPLE

For n = 20, set of palindromic divisors is {1, 2, 4, 5}; a(12) = 1*2*4*5 = 40.

MATHEMATICA

palQ[n_]:=Module[{idn=IntegerDigits[n]}, idn==Reverse[idn]]; f[n_]:=Times@@Select[Divisors[n], palQ]; Table[f[n], {n, 100}] (* Harvey P. Dale, Jan 21 2011 *)

PROG

(Python)

def ispal(n):

return n==int(str(n)[::-1])

def A184392(n):

s=1

for i in range(1, n+1):

if n%i==0 and ispal(i):

s*=i

return s # Indranil Ghosh, Feb 10 2017

CROSSREFS

Cf. A007955, A087990, A087991, A088000, A088001, A179937.