A117059 Palindromes for which the multiplicative digital root is a prime.

2, 3, 5, 7, 121, 131, 151, 171, 232, 474, 535, 575, 666, 929, 999, 3993, 9339, 11211, 11311, 11511, 11711, 12321, 14741, 15351, 15751, 16661, 19291, 19991, 21312, 22722, 23632, 28782, 29392, 32623, 33233, 33933, 35753, 36363, 38383, 39193

Offset

1,1

Links

Table of n, a(n) for n=1..40.

Example

575 is in the sequence because (1) it is a palindrome and (2)the multiplicative digital root is 5, which is a prime.

Mathematica

d[n_] := IntegerDigits[n]; Select[Range[39200], Reverse[y = d[#1]] == y && PrimeQ[NestWhile[Times @@ d[#] &, #1, # > 9 &]] &] (* Jayanta Basu, Jul 13 2013 *)

Crossrefs

Cf. A002113.

Sequence in context: A046713 A119835 A076609 * A117058 A067173 A357262

Adjacent sequences: A117056 A117057 A117058 * A117060 A117061 A117062

Keyword

base,nonn

Author

Luc Stevens (lms022(AT)yahoo.com), Apr 16 2006

Status

approved