A248818 Numbers n such that the digits of antisigma(n) end in phi(n).

3, 20, 39, 119, 224, 351, 799, 879, 1076, 1504, 4064, 6879, 7999, 56847, 169640, 346879, 470975, 893520, 1955776, 7546879, 17604064, 36722175, 79999999, 95546879, 222503984, 580483743, 584057247, 626394816, 7999999999, 17194139104

Offset

1,1

Comments

Similar to A024816 but using antisigma(n) instead of sigma(n).

All the semiprimes of the form 8*10^k-1 are terms. - Giovanni Resta, May 29 2016

Links

Table of n, a(n) for n=1..30.

Example

Antisigma of 879 is (879 * 880) / 2 - sigma(879) = 386760 - 1176 = 385584 and phi(879) = 584.

Maple

with(numtheory): P:=proc(q) local a, n;
for n from 1 to q do then a:=ilog10(phi(n))+1;
if phi(n)=((n*(n+1)/2-sigma(n)) mod 10^a) then print(n);
fi; od; end: P(10^9);

Crossrefs

Cf. A000010, A024816.

Sequence in context: A254501 A031106 A337478 * A268602 A344890 A072472

Adjacent sequences: A248815 A248816 A248817 * A248819 A248820 A248821

Keyword

nonn,base

Author

Paolo P. Lava, Oct 15 2014

Extensions

a(18)-a(30) from Giovanni Resta, May 29 2016

Status

approved