A085869 Numbers n such that n and its digit reversal have the same prime signature.

1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 13, 15, 17, 22, 26, 31, 33, 37, 39, 44, 51, 55, 58, 62, 66, 71, 73, 77, 79, 85, 88, 93, 97, 99, 101, 107, 111, 113, 115, 117, 121, 122, 123, 129, 131, 141, 143, 149, 151, 155, 157, 158, 159, 161, 165, 167, 169, 171, 177, 178, 179, 181

Offset: 1

Author

Amarnath Murthy and Meenakshi Srikanth (menakan_s(AT)yahoo.com), Jul 06 2003

Keywords

• base
• easy
• nonn

Examples

			15 is a member 15 = 3*5 and 51 = 3*17 both have the prime signature p*q, p and q are primes.
		

Links

• Alois P. Heinz, Table of n, a(n) for n = 1..20000

Crossrefs

Cf. A062895.

Programs

Maple

s:= n-> sort(map(i-> i[2], ifactors(n)[2])):
a:= proc(n) option remember; local k; for k from 1+a(n-1) while
      s(k)<>s((p-> parse(cat(seq(p[-i], i=1..length(p)))))(""||k)) do od; k
    end: a(0):=0:
seq(a(n), n=1..80);  # Alois P. Heinz, Mar 09 2018

Extensions

Corrected and extended by Ray Chandler, Aug 08 2003