|
|
A153783
|
|
3 times 11-gonal (or hendecagonal) numbers: 3*n*(9*n-7)/2.
|
|
12
|
|
|
0, 3, 33, 90, 174, 285, 423, 588, 780, 999, 1245, 1518, 1818, 2145, 2499, 2880, 3288, 3723, 4185, 4674, 5190, 5733, 6303, 6900, 7524, 8175, 8853, 9558, 10290, 11049, 11835, 12648, 13488, 14355, 15249, 16170, 17118, 18093, 19095
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
0,2
|
|
LINKS
|
|
|
FORMULA
|
a(n) = (27*n^2 - 21*n)/2 = A051682(n)*3.
a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3).
E.g.f.: (3/2)*x*(2 + 9*x)*exp(x). (End)
|
|
MATHEMATICA
|
Table[3*n*(9*n-7)/2, {n, 0, 25}] (* or *) LinearRecurrence[{3, -3, 1}, {0, 3, 33}, 25] (* G. C. Greubel, Aug 28 2016 *)
|
|
PROG
|
|
|
CROSSREFS
|
Cf. numbers of the form n*(n*k-k+6))/2, this sequence is the case k=27: see Comments lines of A226492.
|
|
KEYWORD
|
easy,nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|