

A064992


a(n) = usigma(n+1)  usigma(n), where usigma(n) is the sum of unitary divisors of n (A034448).


2



2, 1, 1, 1, 6, 4, 1, 1, 8, 6, 8, 6, 10, 0, 7, 1, 12, 10, 10, 2, 4, 12, 12, 10, 16, 14, 12, 10, 42, 40, 1, 15, 6, 6, 2, 12, 22, 4, 2, 12, 54, 52, 16, 0, 12, 24, 20, 18, 28, 6, 2, 16, 30, 12, 0, 8, 10, 30, 60, 58, 34, 16, 15, 19, 60, 76, 22, 6, 48, 72, 18, 16, 40
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OFFSET

1,1


LINKS

Harry J. Smith, Table of n, a(n) for n = 1..1000


FORMULA

a(n) = A034448(n+1)  A034448(n).


PROG

(PARI) usigma(n)= { local(f, s=1); f=factor(n); for(i=1, matsize(f)[1], s*=1 + f[i, 1]^f[i, 2]); return(s) } { u=1; for (n=1, 1000, u1=usigma(n + 1); a=u1  u; u=u1; write("b064992.txt", n, " ", a) ) } \\ Harry J. Smith, Oct 02 2009


CROSSREFS

Cf. A034448.
Sequence in context: A069777 A225816 A227655 * A187783 A089759 A325970
Adjacent sequences: A064989 A064990 A064991 * A064993 A064994 A064995


KEYWORD

sign


AUTHOR

N. J. A. Sloane, Oct 31 2001


STATUS

approved



