A209190 Least prime factor of reversal of digits of n.

1, 2, 3, 2, 5, 2, 7, 2, 3, 1, 11, 3, 31, 41, 3, 61, 71, 3, 7, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 13, 23, 3, 43, 53, 3, 73, 83, 3, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 5, 3, 5, 5, 3, 5, 5, 3, 5, 5, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 7, 17, 3, 37, 47, 3, 67, 7, 3, 97, 2, 2, 2

Offset

1,2

Comments

This is to lpf (A020639) as A210437 is to gpf (A006530). - Jonathan Vos Post, Mar 22 2012

Links

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

PrimeFan, Listing of Esoteric Integer Sequences

Formula

a(n) = A020639(A004086(n)) = lpf(R(n)). - Jonathan Vos Post, Mar 22 2012

Maple

read("transforms") ;
A209190 := proc(n)
        A020639(digrev(n)) ;
end proc:
seq(A209190(n), n=1..100) ; # R. J. Mathar, Mar 22 2012

Mathematica

a[n_] := FactorInteger[IntegerReverse[n]][[1, 1]];
Array[a, 100] (* Jean-François Alcover, Jan 14 2021 *)

Prog

(PARI) lpf(n) = if (n==1, 1, vecmin(factor(n)[, 1]));
a(n) = lpf(fromdigits(Vecrev(digits(n)))); \\ Michel Marcus, Feb 11 2020

Crossrefs

Cf. A004086, A020639, A210437.

Sequence in context: A284694 A072591 A085308 * A086286 A272565 A378157

Adjacent sequences: A209187 A209188 A209189 * A209191 A209192 A209193

Keyword

nonn,base,look

Author

N. J. A. Sloane, Mar 05 2012

Status

approved