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A299410 Numbers that can be expressed both as the sum of first deficient numbers and as the sum of first abundant numbers. 0
30, 8388, 10093090395, 107318445076, 123649798600, 28404836330575, 85678144827202815, 456013868127570451 (list; graph; refs; listen; history; text; internal format)
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

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Last modified August 9 01:35 EDT 2020. Contains 336310 sequences. (Running on oeis4.)