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A276700 Numbers n such that Sum_{p|n} 0.p is an integer where p ranges over the prime divisors, with multiplicity, of n. 2
1, 21, 25, 30, 32, 36, 392, 441, 525, 560, 625, 630, 672, 750, 756, 800, 900, 960, 979, 1024, 1080, 1152, 1215, 1296, 1411, 1458, 1463, 1547, 1742, 1947, 2059, 2090, 2210, 2318, 2405, 2419, 2444, 2491, 2508, 2552, 2652, 2703, 2871, 2886, 2924, 2945, 3116, 3128 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Paolo P. Lava, Table of n, a(n) for n = 1..1000

EXAMPLE

21 = 3 * 7 and 0.3 + 0.7 = 1;

3128 = 2^3 * 17 * 23 and 3*0.2 + 0.17 + 0.23 = 1.

MAPLE

with(numtheory): P:= proc(q) local a, k, n;

for n from 1 to q do a:=ifactors(n)[2];

if type(add(a[k][2]*a[k][1]/10^(ilog10(a[k][1])+1), k=1..nops(a)), integer)

then print(n); fi; od; end: P(10^9);

MATHEMATICA

paiQ[n_]:=IntegerQ[Total[#/10^IntegerLength[#]&/@Flatten[Table[#[[1]], #[[2]]]&/@ FactorInteger[n]]]]; Join[{1}, Select[Range[3200], paiQ]] (* Harvey P. Dale, Apr 02 2020 *)

CROSSREFS

Cf. A276465, A276655, A276699.

Sequence in context: A217150 A274178 A118578 * A181781 A324551 A338081

Adjacent sequences:  A276697 A276698 A276699 * A276701 A276702 A276703

KEYWORD

nonn,base

AUTHOR

Paolo P. Lava, Sep 15 2016

STATUS

approved

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Last modified May 11 12:47 EDT 2021. Contains 343791 sequences. (Running on oeis4.)