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A226451 a(n) = n*(7*n^2-12*n+7)/2. 3
0, 1, 11, 51, 142, 305, 561, 931, 1436, 2097, 2935, 3971, 5226, 6721, 8477, 10515, 12856, 15521, 18531, 21907, 25670, 29841, 34441, 39491, 45012, 51025, 57551, 64611, 72226, 80417, 89205, 98611, 108656, 119361, 130747, 142835, 155646, 169201, 183521 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

See the comment in A226449.

LINKS

Bruno Berselli, Table of n, a(n) for n = 0..1000

Index entries for linear recurrences with constant coefficients, signature (4,-6,4,-1).

FORMULA

G.f.: x*(1+7*x+13*x^2)/(1-x)^4.

a(n) = A001106(n) + n*A001106(n-1).

MATHEMATICA

Table[n (7 n^2 - 12 n + 7)/2, {n, 0, 40}]

CoefficientList[Series[x (1 + 7 x + 13 x^2)/(1 - x)^4, {x, 0, 40}], x] (* Vincenzo Librandi, Aug 18 2013 *)

PROG

(MAGMA) [n*(7*n^2-12*n+7)/2: n in [0..40]];

(MAGMA) I:=[0, 1, 11, 51]; [n le 4 select I[n] else 4*Self(n-1)-6*Self(n-2)+4*Self(n-3)-Self(n-4): n in [1..40]]; // Vincenzo Librandi, Aug 18 2013

CROSSREFS

Cf. A001106.

Similar sequences of the type b(m)+m*b(m-1), where b is a polygonal number: A006003, A069778, A143690, A204674, A212133, A226449, A226450.

Sequence in context: A181619 A067983 A175360 * A185505 A051843 A107464

Adjacent sequences:  A226448 A226449 A226450 * A226452 A226453 A226454

KEYWORD

nonn,easy

AUTHOR

Bruno Berselli, Jun 07 2013

STATUS

approved

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Last modified January 23 19:45 EST 2020. Contains 331175 sequences. (Running on oeis4.)