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A244802 The 60-degree 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
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
Sequence in context: A084036 A092117 A245663 * A336288 A211070 A251936
KEYWORD
nonn,easy
AUTHOR
Robert G. Wilson v, Jul 06 2014
STATUS
approved

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Last modified July 19 03:15 EDT 2024. Contains 374388 sequences. (Running on oeis4.)