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A081271 Vertical of triangular spiral in A051682. 6
1, 13, 34, 64, 103, 151, 208, 274, 349, 433, 526, 628, 739, 859, 988, 1126, 1273, 1429, 1594, 1768, 1951, 2143, 2344, 2554, 2773, 3001, 3238, 3484, 3739, 4003, 4276, 4558, 4849, 5149, 5458, 5776, 6103, 6439, 6784, 7138, 7501, 7873, 8254, 8644, 9043, 9451 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Lies to the right of the y-axis of the triangle.

Binomial transform of (1, 12, 9, 0, 0, 0, ...).

LINKS

Table of n, a(n) for n=0..45.

Index entries for linear recurrences with constant coefficients, signature (3,-3,1).

FORMULA

G.f.: (1 + 10*x - 2*x^2)/(1 - x)^3.

a(n) = binomial(n, 0) + 12*binomial(n, 1) + 9*binomial(n, 2).

a(n) = (9*n^2 + 15*n + 2)/2.

a(0) = 1, a(n) = a(n-1) + 9*n + 3 for n > 0 - Gerald McGarvey, Aug 18 2004

PROG

(PARI) a(n)=(9*n^2+15*n+2)/2 \\ Charles R Greathouse IV, Jun 17 2017

CROSSREFS

Cf. A062741.

Cf. A283394 (see Crossrefs section).

Sequence in context: A134864 A093100 A292472 * A190458 A180673 A081752

Adjacent sequences:  A081268 A081269 A081270 * A081272 A081273 A081274

KEYWORD

nonn,easy

AUTHOR

Paul Barry, Mar 15 2003

STATUS

approved

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Last modified May 26 20:51 EDT 2022. Contains 354092 sequences. (Running on oeis4.)