A376545 - OEIS

A376545

Least prime factor of A252043(n) for n > 1 with a(1) = 1.

1, 2, 3, 2, 3, 2, 127, 2, 3, 1234567891, 2, 9091, 3, 12345678910111, 2, 17, 113, 7, 2, 19, 3, 7, 2, 123456789101112131415161, 3, 13, 2, 17, 13, 2, 2, 2, 3, 2, 2, 2, 3, 2, 2, 2, 5, 2, 2, 2, 3, 2, 2, 2, 3, 3, 2, 3, 29, 547, 2, 3, 3, 3, 2, 31, 3, 3, 2, 3, 71, 7

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,2

LINKS

Table of n, a(n) for n=1..66.

Micha Fleuren, Smarandache Factors and Reverse Factors.

FORMULA

a(n) = A020639(A252043(n)).

EXAMPLE

A252043(3) = 123 = 3 * 41, so a(3) = 3.

PROG

(PARI) a(n) = my(list=List(), k=1); while(#list<n, my(d=digits(k)); for (i=1, #d, listput(list, d[i])); k++; ); my(m=fromdigits(Vec(list, n))); if (m==1, 1, vecmin(factor(m)[, 1])); \\ Michel Marcus, Sep 29 2024

CROSSREFS

Cf. A020639, A252043, A376274.

Sequence in context: A119880 A075019 A138960 * A245553 A370455 A115397

Adjacent sequences: A376541 A376542 A376543 * A376546 A376547 A376548

KEYWORD

nonn,base

AUTHOR

Jean-Marc Rebert, Sep 27 2024

STATUS

approved