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A210437 Greatest prime factor of reversal of digits of n. 3
1, 2, 3, 2, 5, 3, 7, 2, 3, 1, 11, 7, 31, 41, 17, 61, 71, 3, 13, 2, 3, 11, 2, 7, 13, 31, 3, 41, 23, 3, 13, 23, 11, 43, 53, 7, 73, 83, 31, 2, 7, 3, 17, 11, 3, 2, 37, 7, 47, 5, 5, 5, 7, 5, 11, 13, 5, 17, 19, 3, 2, 13, 3, 23, 7, 11, 19, 43, 3, 7, 17, 3, 37, 47, 19 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Alois P. Heinz, Table of n, a(n) for n = 1..12000

FORMULA

a(n) = A006530(A004086(n)) = gpf(R(n)). - Jonathan Vos Post, Mar 22 2012

MAPLE

with(numtheory):

r:= proc(n) option remember; local q;

      `if`(n<10, n, irem(n, 10, 'q')*10^(length(n)-1) +r(q))

    end:

a:= n-> `if`(r(n)=1, 1, max(factorset(r(n))[])):

seq(a(n), n=1..100);

MATHEMATICA

FactorInteger[FromDigits[Reverse[IntegerDigits[#]]]][[-1, 1]]&/@Range[80] (* Harvey P. Dale, Sep 14 2014 *)

PROG

(PARI) gpf(n) = if (n==1, 1, vecmax(factor(n)[, 1]));

a(n) = gpf(fromdigits(Vecrev(digits(n)))); \\ Michel Marcus, Feb 11 2020

CROSSREFS

Cf. A004086, A006530, A209190.

Sequence in context: A078834 A039634 A078833 * A109674 A284260 A218993

Adjacent sequences:  A210434 A210435 A210436 * A210438 A210439 A210440

KEYWORD

nonn,look,base

AUTHOR

Alois P. Heinz, Mar 21 2012

STATUS

approved

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Last modified September 25 15:27 EDT 2021. Contains 347658 sequences. (Running on oeis4.)