A248819 Numbers n such that the digits of antisigma(n) end in sigma(n).

79, 479, 2879, 4895, 26879, 79999, 644735, 799999, 2395488, 6399839, 8598719, 63652895, 144726608, 799999999, 935546879, 12640160863, 15282380799, 43687707904, 79999999999

Offset: 1

Author

Paolo P. Lava, Oct 15 2014

Keywords

• nonn
• more
• base

Comments

All the primes of the form 8*10^k-1 for k>0 are terms (A056721). - Giovanni Resta, May 29 2016

Examples

			sigma(4895) = 6480 and antisigma of 4895 is (4895 * 4896) / 2 - sigma(4895) = 11982960 - 6480 = 11976480.
		

Crossrefs

Cf. A000230, A024816, A056721.

Programs

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);

Extensions

a(9)-a(19) from Giovanni Resta, May 29 2016