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A065805 a(n) = Sum_{j=0..n} sigma(j,n). 3
2, 10, 44, 377, 3912, 57214, 960808, 19261862, 435877584, 11123320200, 313842837684, 9729290348250, 328114698808288, 11967567841654610, 469172063576559648, 19676848703371278527, 878942778254232811956 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

PARI calls it sigma(n, j). - Harry J. Smith, Oct 31 2009

LINKS

Harry J. Smith, Table of n, a(n) for n = 1..100

FORMULA

a(n) ~ n^(n+1) / (n-1). - Vaclav Kotesovec, Sep 11 2018

EXAMPLE

n=6; a(6) = 4 + 12 + 50 + 252 + 1394 + 8052 + 47450 = 57214.

MATHEMATICA

a[ n ]=Table[ Apply[ Plus, Table[ DivisorSigma[ w, n ], {w, 0, n} ] ].

PROG

(PARI) { for (n=1, 100, a=sum(j=0, n, sigma(n, j)); write("b065805.txt", n, " ", a) ) } \\ Harry J. Smith, Oct 31 2009

CROSSREFS

Cf. A000005, A000203, A001157, A319194.

Sequence in context: A144896 A142983 A227852 * A145239 A068561 A068484

Adjacent sequences:  A065802 A065803 A065804 * A065806 A065807 A065808

KEYWORD

nonn

AUTHOR

Labos Elemer, Nov 21 2001

STATUS

approved

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Last modified January 25 01:41 EST 2020. Contains 331229 sequences. (Running on oeis4.)