OFFSET
1,1
COMMENTS
Proposed by Jaroslav Krizek in A260071.
LINKS
Giovanni Resta, Table of n, a(n) for n = 1..33 (terms < 10^13)
FORMULA
a(n) = A246852(n) + 1.
MATHEMATICA
Select[Range@ 1000000, DivisorSigma[1, # + 1] - DivisorSigma[1, # - 1] == # + 1 &] (* Michael De Vlieger, Jul 25 2015 *)
PROG
(PARI) for(n=2, 1e9, sigma(n+1)-sigma(n-1)==n+1&&print1(n", "))
(Magma) [n: n in [2..5*10^6] | DivisorSigma(1, n+1) - DivisorSigma(1, n-1) eq n+1]; // Vincenzo Librandi, Jul 26 2015
CROSSREFS
KEYWORD
nonn
AUTHOR
M. F. Hasler, Jul 25 2015
STATUS
approved