A305980 - OEIS

A305980

Filter sequence for a(Squarefree numbers > 1) = constant sequences.

1, 2, 2, 3, 2, 2, 2, 4, 5, 2, 2, 6, 2, 2, 2, 7, 2, 8, 2, 9, 2, 2, 2, 10, 11, 2, 12, 13, 2, 2, 2, 14, 2, 2, 2, 15, 2, 2, 2, 16, 2, 2, 2, 17, 18, 2, 2, 19, 20, 21, 2, 22, 2, 23, 2, 24, 2, 2, 2, 25, 2, 2, 26, 27, 2, 2, 2, 28, 2, 2, 2, 29, 2, 2, 30, 31, 2, 2, 2, 32, 33, 2, 2, 34, 2, 2, 2, 35, 2, 36, 2, 37, 2, 2, 2, 38, 2, 39, 40, 41, 2, 2, 2, 42, 2, 2, 2, 43, 2, 2, 2

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

OFFSET

1,2

COMMENTS

For all i, j: A305800(i) = A305800(j) => a(i) = a(j).

LINKS

Antti Karttunen, Table of n, a(n) for n = 1..100000

FORMULA

a(1) = 1; for n > 1, if A008966(n) = 1 [when n is in A005117], then a(n) = 2, otherwise a(n) = 2+A057627(n).

PROG

(PARI)

up_to = 100000;