A064598 - OEIS

A064598

Nonunitary deficient numbers: the sum of the nonunitary divisors of n is less than n; i.e., sigma(n) - usigma(n) < n.

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 73, 74, 75, 76

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

OFFSET

1,2

LINKS

Amiram Eldar, Table of n, a(n) for n = 1..10000 (terms 1..1000 from Harry J. Smith)

MATHEMATICA

nusigma[ n_ ] := DivisorSigma[ 1, n ]-Times@@(1+Power@@#&/@FactorInteger[ n ]); For[ n=1, True, n++, If[ nusigma[ n ]<n, Print[ 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) } { n=0; for (m=1, 10^9, if (sigma(m) - usigma(m) < m, write("b064598.txt", n++, " ", m); if (n==1000, break)) ) } \\ Harry J. Smith, Sep 19 2009

CROSSREFS

Cf. A048146, A064591, A064597.

Sequence in context: A328617 A230308 A357875 * A366187 A364354 A289555

Adjacent sequences: A064595 A064596 A064597 * A064599 A064600 A064601

KEYWORD

nonn,easy

AUTHOR

Dean Hickerson, Sep 25 2001

STATUS

approved