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A085869 Numbers n such that n and its digit reversal have the same prime signature. 5
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 (list; graph; refs; listen; history; text; internal format)
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: A289351 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

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Last modified September 25 22:56 EDT 2022. Contains 356986 sequences. (Running on oeis4.)