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A143272
a(n) = d(n)*T(n), where d(n) is the number of divisors of n (A000005) and T(n)=n(n+1)/2 are the triangular numbers (A000217).
3
1, 6, 12, 30, 30, 84, 56, 144, 135, 220, 132, 468, 182, 420, 480, 680, 306, 1026, 380, 1260, 924, 1012, 552, 2400, 975, 1404, 1512, 2436, 870, 3720, 992, 3168, 2244, 2380, 2520, 5994, 1406, 2964, 3120, 6560, 1722, 7224, 1892, 5940, 6210, 4324, 2256, 11760
OFFSET
1,2
LINKS
FORMULA
Equals row sums of triangle A143271
EXAMPLE
a(4) = 30 = d(4)*T(4) = 3*10, where A000005 = (1, 2, 2, 3, 2, 4, ...) and A000217 = (1, 3, 6, 10, ...).
MAPLE
with(numtheory): seq((1/2)*tau(n)*n*(n+1), n=1..50); # Emeric Deutsch, Aug 16 2008
MATHEMATICA
Table[DivisorSigma[0, n] (n(n+1))/2, {n, 50}] (* Harvey P. Dale, Sep 05 2017 *)
PROG
(PARI) a(n) = numdiv(n)*n*(n+1)/2; \\ Michel Marcus, Mar 11 2019
CROSSREFS
KEYWORD
nonn
AUTHOR
Gary W. Adamson, Aug 03 2008
EXTENSIONS
Extended by Emeric Deutsch, Aug 16 2008
STATUS
approved