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A086669
a(n) = number of divisors of n that are fundamental discriminants.
4
1, 1, 1, 1, 2, 1, 1, 2, 1, 2, 1, 2, 2, 1, 2, 2, 2, 1, 1, 2, 2, 1, 1, 4, 2, 2, 1, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 1, 2, 4, 2, 2, 1, 2, 2, 1, 1, 4, 1, 2, 2, 2, 2, 1, 2, 4, 2, 2, 1, 4, 2, 1, 2, 2, 4, 2, 1, 2, 2, 2, 1, 4, 2, 2, 2, 2, 2, 2, 1, 4, 1, 2, 1, 4, 4, 1, 2, 4, 2, 2, 2, 2, 2, 1, 2, 4, 2, 1, 2, 2
OFFSET
1,5
LINKS
FORMULA
a(n) = Sum_{d|n} A290098(d).
EXAMPLE
10 has divisors 1, 2, 5 and 10 of which 1 and 5 are fundamental discriminants, so a(10)=2
PROG
(PARI) for (n=1, 100, s=0; fordiv(i=n, i, s+=isfundamental(i)); print1(", "s))
(PARI) A086669(n) = sumdiv(n, i, isfundamental(i)); \\ Antti Karttunen, Aug 22 2017
CROSSREFS
Sequence in context: A103684 A105103 A376365 * A357906 A053574 A321944
KEYWORD
nonn
AUTHOR
Jon Perry, Jul 27 2003
STATUS
approved