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A244802 The 60º spoke (or ray) of a hexagonal spiral of Ulam. 7
1, 10, 43, 100, 181, 286, 415, 568, 745, 946, 1171, 1420, 1693, 1990, 2311, 2656, 3025, 3418, 3835, 4276, 4741, 5230, 5743, 6280, 6841, 7426, 8035, 8668, 9325, 10006, 10711, 11440, 12193, 12970, 13771, 14596, 15445, 16318, 17215, 18136, 19081, 20050, 21043, 22060, 23101, 24166, 25255 (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 + 7*x + 16*x^2) / (1 - x)^3.

(End)

EXAMPLE

See A056105 example section for a diagram.

MAPLE

A244802:=n->12*n^2-27*n+16: seq(A244802(n), n=1..50); # Wesley Ivan Hurt, Jul 06 2014

MATHEMATICA

f[n_] := 12n^2 - 27n + 16; Array[f, 47]

PROG

(PARI) vector(50, n, 12*n^2 - 27*n + 16) \\ Michel Marcus, Jul 06 2014

(PARI) Vec(x*(1 + 7*x + 16*x^2) / (1 - x)^3 + O(x^50)) \\ Colin Barker, Dec 12 2016

(MAGMA) [12*n^2-27*n+16 : n in [1..50]]; // Wesley Ivan Hurt, Jul 06 2014

CROSSREFS

Cf. A056105, A056106, A244803, A056107, A244804, A056108, A244805, A056109, A244806, A003215.

Sequence in context: A084036 A092117 A245663 * A211070 A251936 A187673

Adjacent sequences:  A244799 A244800 A244801 * A244803 A244804 A244805

KEYWORD

nonn,easy

AUTHOR

Robert G. Wilson v, Jul 06 2014

STATUS

approved

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Last modified December 17 14:12 EST 2018. Contains 318201 sequences. (Running on oeis4.)