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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 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Interleaves the odd squares A016754 with 8 times the triangular numbers A000217.

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 0..10000

Index entries for linear recurrences with constant coefficients, signature (1,2,-2,-1,1).

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

Cf. A081350, A081352.

Sequence in context: A256932 A304600 A278076 * A032462 A077599 A109097

Adjacent sequences:  A081348 A081349 A081350 * A081352 A081353 A081354

KEYWORD

nonn,easy

AUTHOR

Paul Barry, Mar 19 2003

STATUS

approved

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Last modified August 17 17:00 EDT 2019. Contains 326059 sequences. (Running on oeis4.)