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A081351
First row in square maze array of natural numbers A081349.
5
1, 8, 9, 24, 25, 48, 49, 80, 81, 120, 121, 168, 169, 224, 225, 288, 289, 360, 361, 440, 441, 528, 529, 624, 625, 728, 729, 840, 841, 960, 961, 1088, 1089, 1224, 1225, 1368, 1369, 1520, 1521, 1680, 1681, 1848, 1849, 2024, 2025, 2208, 2209, 2400, 2401, 2600
OFFSET
0,2
COMMENTS
Interleaves the odd squares A016754 with 8 times the triangular numbers A000217.
FORMULA
a(n) = (n+1)*(n+2)-(n+1)*(-1)^n = 2*C(n+2,2)-C(n+1,1)*(-1)^n.
G.f.: (x^3-x^2+7*x+1)/((1-x)^3*(1+x)^2). [Colin Barker, Sep 03 2012]
PROG
(Magma) [(n+1)*(n+2)-(n+1)*(-1)^n: n in [0..50]]; // Vincenzo Librandi, Sep 06 2011
CROSSREFS
Sequence in context: A256932 A304600 A278076 * A032462 A077599 A109097
KEYWORD
nonn,easy
AUTHOR
Paul Barry, Mar 19 2003
STATUS
approved