OFFSET
1,1
COMMENTS
a(37) > 10^12. - Donovan Johnson, Sep 02 2013
Conjecture: a(p) = 2^(p-1) * k - 1 for some k > 0 and prime p. - David A. Corneth, Jan 26 2021
LINKS
David A. Corneth, Table of n, a(n) for n = 1..196
Donovan Johnson, All 435 terms <= 10^12
FORMULA
a(n) = Min_{x : d[x+1]/d[x] = n}.
a(n) = A086551(n) - 1. - Hugo Pfoertner, Jan 26 2021
EXAMPLE
n = 49: a(49) = 233279 = m, d(m+1) = 98, d(m) = 2, quotient = 49.
MATHEMATICA
t = Table[ 0, {50}]; Do[ s = DivisorSigma[0, n+1] / DivisorSigma[0, n]; If[ s < 51 && t[[s]] == 0, t[[s]] = n], {n, 1, 10^8}]; t
PROG
(PARI) {a(n) = my(k=1); while(numdiv(k+1)!=n*numdiv(k), k++); k} \\ Seiichi Manyama, Jan 17 2021
CROSSREFS
KEYWORD
nonn
AUTHOR
Labos Elemer, Feb 24 2003
EXTENSIONS
More terms from Robert G. Wilson v, Feb 27 2003
a(29) and a(31) from Donovan Johnson, Dec 26 2012
More terms from David A. Corneth, Jan 27 2021
STATUS
approved