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A244803 The 360º spoke (or ray) of a hexagonal spiral of Ulam. 7
1, 12, 47, 106, 189, 296, 427, 582, 761, 964, 1191, 1442, 1717, 2016, 2339, 2686, 3057, 3452, 3871, 4314, 4781, 5272, 5787, 6326, 6889, 7476, 8087, 8722, 9381, 10064, 10771, 11502, 12257, 13036, 13839, 14666, 15517, 16392, 17291, 18214, 19161, 20132, 21127, 22146, 23189, 24256, 25347 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Colin Barker, Table of n, a(n) for n = 1..1000

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

FORMULA

See A056105 example section for a formula.

From Colin Barker, Dec 12 2016: (Start)

a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3) for n>3.

G.f.: x*(1 + 2*x)*((1 + 7*x) / (1 - x)^3).

(End)

EXAMPLE

See A056105 example section for a diagram.

MAPLE

A244803:=n->12*n^2-25*n+14: seq(A244803(n), n=1..50); # Wesley Ivan Hurt, Jul 06 2014

MATHEMATICA

f[n_] := 12n^2 - 25n + 14; Array[f, 47]

PROG

(PARI) vector(50, n, 12*n^2 - 25*n + 14) \\ Michel Marcus, Jul 06 2014

(PARI) Vec(x*(1 + 2*x)*((1 + 7*x) / (1 - x)^3) + O(x^50)) \\ Colin Barker, Dec 12 2016

(MAGMA) [12*n^2-25*n+14 : n in [1..50]]; // Wesley Ivan Hurt, Jul 06 2014

CROSSREFS

Cf. A056105, A244802, A056106, A056107, A244804, A056108, A244805, A056109, A244806, A003215, A033577.

Sequence in context: A197471 A159013 A022281 * A024183 A051673 A030623

Adjacent sequences:  A244800 A244801 A244802 * A244804 A244805 A244806

KEYWORD

nonn,easy

AUTHOR

Robert G. Wilson v, Jul 06 2014

STATUS

approved

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Last modified December 14 05:17 EST 2018. Contains 318090 sequences. (Running on oeis4.)