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1, 7, 13, 31, 43, 73, 91, 133, 157, 211, 241, 307, 343, 421, 463, 553, 601, 703, 757, 871, 931, 1057, 1123, 1261, 1333, 1483, 1561, 1723, 1807, 1981, 2071, 2257, 2353, 2551, 2653, 2863, 2971, 3193, 3307, 3541, 3661, 3907, 4033, 4291, 4423, 4693, 4831, 5113, 5257, 5551, 5701, 6007, 6163, 6481
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history;
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OFFSET
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0,2
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LINKS
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Robert Israel, Table of n, a(n) for n = 0..10000
Index entries for linear recurrences with constant coefficients, signature (1,2,-2,-1,1).
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FORMULA
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From Robert Israel, Jan 21 2018: (Start)
G.f.: (1+6*x+4*x^2+6*x^3+x^4)/((1+x)^2*(1-x)^3).
a(n) = (4+6*n+9*n^2)/4 if n is even, (7+12*n+9*n^2)/4 if n is odd. (End)
Sequence equals values of 9m^2 + 3m + 1 for m = 0, -1, 1, -2, 2, -3, 3, ... . - Greg Dresden, Jul 02 2018
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MAPLE
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seq((4+6*n+9*n^2+(3+6*n)*(n mod 2))/4, n=0..100); # Robert Israel, Jan 21 2018
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MATHEMATICA
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Sort[Table[9 m^2 + 3 m + 1, {m, -20, 20}]] (* Greg Dresden, Jul 02 2018 *)
Accumulate[LinearRecurrence[{0, 2, 0, -1}, {1, 6, 6, 18, 12}, 80]] (* Harvey P. Dale, Oct 02 2020 *)
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CROSSREFS
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Cf. A298026.
Sequence in context: A110912 A240680 A308851 * A085104 A162652 A306889
Adjacent sequences: A298024 A298025 A298026 * A298028 A298029 A298030
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KEYWORD
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nonn
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AUTHOR
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N. J. A. Sloane, Jan 21 2018
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STATUS
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approved
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