OFFSET
1,1
LINKS
Donovan Johnson and Giovanni Resta, Table of n, a(n) for n = 1..170 (terms < 10^13, first 50 terms from Donovan Johnson)
FORMULA
a(n) = A076528(n)-1 - Alex Ratushnyak, Jul 06 2013.
MATHEMATICA
s1 = s2 = s3 = 0; Do[ s1 = s2; s2 = s3; s3 = DivisorSigma[1, n]; If[ s2 == s1 + s3, Print[n - 1]], {n, 1, 10^8}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Benoit Cloitre, Aug 27 2002
EXTENSIONS
Edited and extended by Robert G. Wilson v, Oct 24 2002
a(25)-a(26) from Donovan Johnson, Feb 01 2009
STATUS
approved