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A179528 Number of terms of A083207 that are not greater than n. 4
0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 7, 7, 8, 8, 8, 8, 8, 8, 9, 9, 9, 9, 9, 9, 10, 10, 11, 11, 11, 11, 12, 12, 12, 12, 12, 12, 13, 13, 13, 13, 14, 14, 14, 14, 14, 14, 14, 14, 15, 15, 16, 16, 16, 16, 17, 17, 17, 17 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,12

COMMENTS

Partial sums of A179527: a(n) = SUM(A179527(k): 1<=k<=n);

A179529(n+1) = a(n+12) - a(n).

LINKS

R. Zumkeller, Table of n, a(n) for n = 1..10000

Peter Luschny, Zumkeller Numbers

EXAMPLE

a(100)=#{6,12,20,24,28,30,40,42,48,54,56,60,66,70,78,80,84,88,90,96}=20;

a(1000000)=229026, by T. D. Noe.

MATHEMATICA

ZumkellerQ[n_] := Module[{d = Divisors[n], t, ds, x}, ds = Total[d]; If[Mod[ds, 2] > 0, False, t = CoefficientList[Product[1 + x^i, {i, d}], x]; t[[1 + ds/2]] > 0]];

b[n_] := Boole[ZumkellerQ[n]];

Array[b, 100] // Accumulate (* Jean-Fran├žois Alcover, Apr 30 2017, after T. D. Noe *)

CROSSREFS

Sequence in context: A111898 A279041 A072746 * A105390 A013941 A061798

Adjacent sequences:  A179525 A179526 A179527 * A179529 A179530 A179531

KEYWORD

nonn

AUTHOR

Reinhard Zumkeller, Jul 19 2010

STATUS

approved

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Last modified November 20 08:16 EST 2018. Contains 317385 sequences. (Running on oeis4.)