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A076755 Nearest integer to the kurtosis excess of the divisors of n. 1
1, 1, 2, 1, 2, 1, 2, 2, 2, 1, 3, 1, 2, 2, 2, 1, 3, 1, 3, 2, 2, 1, 4, 2, 2, 2, 3, 1, 4, 1, 3, 2, 2, 2, 4, 1, 2, 2, 4, 1, 4, 1, 3, 4, 2, 1, 5, 2, 3, 2, 3, 1, 4, 2, 4, 2, 2, 1, 6, 1, 2, 4, 3, 2, 4, 1, 3, 2, 4, 1, 6, 1, 2, 3, 3, 2, 4, 1, 5, 3, 2, 1, 6, 2, 2, 2, 4, 1, 6, 2, 3, 2, 2, 2, 6, 1, 3, 4, 4, 1, 4, 1, 4, 5, 2 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,3

COMMENTS

Kurtosis measures the concentration of data around the peak and in the tails versus the concentration in the flanks and is defined to be the fourth central moment divided by the square of the variance.

LINKS

Hans Havermann, Table of n, a(n) for n = 2..10000

MATHEMATICA

Table[Round[Kurtosis[Divisors[n]]], {n, 2, 150}]

PROG

(PARI) a(n)=local(s0, s1, s2, s3, s4); s0=numdiv(n); s1=sigma(n); s2=sigma(n, 2); s3=sigma(n, 3); s4=sigma(n, 4); if(n<2, 0, round(-3+s0^2*(s4*s0-4*s3*s1+3*s2^2)/(s0*s2 -s1^2)^2))

CROSSREFS

Sequence in context: A128428 A056171 A238949 * A317751 A106490 A122375

Adjacent sequences:  A076752 A076753 A076754 * A076756 A076757 A076758

KEYWORD

nonn

AUTHOR

Joseph L. Pe, Nov 12 2002

STATUS

approved

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Last modified June 19 19:11 EDT 2019. Contains 324222 sequences. (Running on oeis4.)