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A083539
a(n) = sigma(n) * sigma(n+1): product of sigma-values for consecutive integers.
9
3, 12, 28, 42, 72, 96, 120, 195, 234, 216, 336, 392, 336, 576, 744, 558, 702, 780, 840, 1344, 1152, 864, 1440, 1860, 1302, 1680, 2240, 1680, 2160, 2304, 2016, 3024, 2592, 2592, 4368, 3458, 2280, 3360, 5040, 3780, 4032, 4224, 3696, 6552, 5616, 3456, 5952
OFFSET
1,1
LINKS
FORMULA
a(n) = A000203(A002378(n)). - Amiram Eldar, Jul 10 2024
MATHEMATICA
f[x_] := DivisorSigma[1, x]; t=Table[f[w+1]*f[w], {w, 1, 128}]
Times@@@Partition[DivisorSigma[1, Range[50]], 2, 1] (* Harvey P. Dale, May 21 2014 *)
PROG
(PARI) a(n)=sigma(n)*sigma(n+1) \\ Charles R Greathouse IV, Feb 14 2013
CROSSREFS
Cf. A000203, A002378, A060781, A060780, A083538, A330322 (partial sums).
Sequence in context: A083543 A083538 A060781 * A237426 A066643 A140065
KEYWORD
nonn,easy
AUTHOR
Labos Elemer, May 21 2003
STATUS
approved