A299410 Numbers that can be expressed both as the sum of first deficient numbers and as the sum of first abundant numbers.

30, 8388, 10093090395, 107318445076, 123649798600, 28404836330575, 85678144827202815, 456013868127570451

Offset

1,1

Comments

Intersection of A173106 and A173107.

Links

Table of n, a(n) for n=1..8.

Example

The first seven deficient numbers sum to 1 + 2 + 3 + 4 + 5 + 7 + 8 = 30 and the first two abundant numbers sum to 12 + 18 = 30.
The sum of first 113 deficient numbers and the sum of first 61 abundant numbers are equal to 8388.

Maple

with(numtheory): P:=proc(q) local a, b, c, d, n; a:=0; b:=0; c:=0; d:=0;
for n from 1 to q do b:=b+1; while sigma(b)<=2*b do b:=b+1; od; a:=a+b;
while c<a do d:=d+1; if sigma(d)<2*d then c:=c+d; fi; od;
if c=a then print(a); fi; od; end: P(10^9);

Crossrefs

Cf. A005100, A005101, A173106, A173107.

Sequence in context: A239925 A059049 A056071 * A294976 A294975 A294979

Adjacent sequences: A299407 A299408 A299409 * A299411 A299412 A299413

Keyword

nonn,more

Author

Paolo P. Lava, Feb 26 2018

Extensions

a(6)-a(8) from Giovanni Resta, Feb 26 2018

Status

approved