OFFSET
1,1
COMMENTS
All the primes of the form 8*10^k-1 for k>0 are terms (A056721). - Giovanni Resta, May 29 2016
EXAMPLE
sigma(4895) = 6480 and antisigma of 4895 is (4895 * 4896) / 2 - sigma(4895) = 11982960 - 6480 = 11976480.
MAPLE
with(numtheory): P:=proc(q) local a, n;
for n from 1 to q do then a:=ilog10(sigma(n))+1;
if sigma(n)=((n*(n+1)/2-sigma(n)) mod 10^a) then print(n);
fi; od; end: P(10^9);
CROSSREFS
KEYWORD
nonn,more,base
AUTHOR
Paolo P. Lava, Oct 15 2014
EXTENSIONS
a(9)-a(19) from Giovanni Resta, May 29 2016
STATUS
approved