

A110751


Numbers n such that n and its digital reversal have the same prime divisors.


14



1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 22, 33, 44, 55, 66, 77, 88, 99, 101, 111, 121, 131, 141, 151, 161, 171, 181, 191, 202, 212, 222, 232, 242, 252, 262, 272, 282, 292, 303, 313, 323, 333, 343, 353, 363, 373, 383, 393, 404, 414, 424, 434, 444, 454, 464, 474, 484, 494
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OFFSET

1,2


COMMENTS

Contains the palindromes A002113 as a subsequence. 1089 and 2178 are the first two nonpalindromic terms. Any number of concatenations of 1089 with itself or 2178 with itself gives a term; e.g. 10891089 etc. Hence there are infinitely many nonpalindromic terms. They are given in A110819.


LINKS

Derek Orr, Table of n, a(n) for n = 1..1000


EXAMPLE

1089 = 3^2*11^2, 9801 = 3^4*11^2.


MATHEMATICA

Select[ Range[ 500], First /@ FactorInteger[ # ] == First /@ FactorInteger[ FromDigits[ Reverse[ IntegerDigits[ # ]]]] &] (* Robert G. Wilson v *)


PROG

(PARI) is_A110751(n)={ local(r=eval(concat(vecextract(Vec(Str(n)), "1..1")))); r==n  factor(r)[, 1]==factor(n)[, 1] } /* M. F. Hasler */
(Python)
from sympy import primefactors
A110751 = [n for n in range(1, 10**5) if primefactors(n) == primefactors(int(str(n)[::1]))] # Chai Wah Wu, Aug 14 2014


CROSSREFS

Cf. A002113, A110819.
Sequence in context: A342826 A266140 A297271 * A147882 A002113 A227858
Adjacent sequences: A110748 A110749 A110750 * A110752 A110753 A110754


KEYWORD

base,easy,nonn


AUTHOR

Amarnath Murthy, Aug 11 2005


EXTENSIONS

Edited and extended by Robert G. Wilson v, Sep 21 2005
Corrected comment, added PARI code.  M. F. Hasler, Nov 16 2008


STATUS

approved



