OFFSET
1,1
COMMENTS
EXAMPLE
The deficiency of 46^2 is 2*46^2 - sigma(46^2) = 19^2, so 46 is a term of the sequence.
MAPLE
issq := n -> evalb(n>1 and issqr(n)):
A033879 := n -> 2*n - numtheory[sigma](n):
isa := n -> issq(A033879(n^2)):
select(isa, [$1..2000]); # Peter Luschny, Jul 25 2017
PROG
(PARI) isok(n) = issquare(d = 2*n^2 - sigma(n^2)) && (d!=1); \\ Michel Marcus, Jul 25 2017
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Jens Voß, Jun 30 2017
EXTENSIONS
a(10) from Chai Wah Wu, Jul 26 2017
a(11)-a(19) from Giovanni Resta, Jul 27 2017
STATUS
approved