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A316098 Abundant numbers that differ from the next abundant number by 4. 4
20, 36, 56, 66, 80, 84, 96, 104, 108, 140, 156, 176, 192, 200, 204, 216, 224, 260, 272, 276, 300, 308, 320, 336, 360, 368, 380, 392, 396, 416, 440, 444, 456, 464, 476, 486, 500, 516, 528, 540, 546, 560, 572, 576, 608, 612, 620, 636, 644, 650, 680, 696, 704 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Muniru A Asiru, Table of n, a(n) for n = 1..10000

EXAMPLE

20 is abundant, 21, 22 and 23 are deficient, 24 is abundant.

36 is abundant, 37, 38 and 39 are deficient, 40 is abundant.

MAPLE

with(numtheory):  A:=select(n->sigma(n)>2*n, [$1..800]): a:=seq(A[i], i in select(n->A[n+1]-A[n]=4, [$1..nops(A)-1]));

MATHEMATICA

q[n_] := DivisorSigma[1, n] > 2 n; Select[Range[704], q[#] && q[# + 4] && ! q[# + 1] && ! q[# + 2] && ! q[# + 3] &] (* Giovanni Resta, Jul 01 2018 *)

PROG

(GAP) A:=Filtered([1..800], n->Sigma(n)>2*n);;  a:=List(Filtered([1..Length(A)-1], i->A[i+1]-A[i]=4), j->A[j]);

CROSSREFS

Subsequence of A005101.

Abundant numbers that differ from the next abundant number by k: A096399 (k=1), A228382 (k=3), this sequence (k=4), A306497 (k=5), A316099 (k=6).

Sequence in context: A135801 A078210 A174628 * A308664 A184065 A259734

Adjacent sequences:  A316095 A316096 A316097 * A316099 A316100 A316101

KEYWORD

nonn

AUTHOR

Muniru A Asiru, Jun 25 2018

STATUS

approved

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Last modified September 24 09:10 EDT 2021. Contains 347630 sequences. (Running on oeis4.)