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

1,2

Links

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

Example

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

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

Crossrefs

Cf. A062895.

Sequence in context: A362038 A171550 A062895 * A068892 A106801 A242417

Adjacent sequences: A085866 A085867 A085868 * A085870 A085871 A085872

Keyword

base,easy,nonn

Author

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

Extensions

Corrected and extended by Ray Chandler, Aug 08 2003

Status

approved