OFFSET
1,2
COMMENTS
Supersequence of A000668 for k=1 (Mersenne primes), A067803 for k=-1 (numbers n such that sigma(n) - sigma(n+1) = n) and A002961 for k=0 (numbers n such that n and n+1 have same sum of divisors). For number 1 is k=2.
Corresponding values of integers k: 2, 1, 1, 0, 1, 1, 0, -1, -1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,....
LINKS
Donovan Johnson, Table of n, a(n) for n = 1..1000
EXAMPLE
Number 532 is in sequence because sigma(533) - sigma(532) = 588 - 1120 = -532 = (-1) * 532; k = -1.
MATHEMATICA
Select[Range[10000], IntegerQ[(DivisorSigma[1, # + 1] - DivisorSigma[1, #])/#] &] (* T. D. Noe, May 02 2013 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Jaroslav Krizek, May 01 2013
EXTENSIONS
Extended by T. D. Noe, May 02 2013
STATUS
approved