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A061525 Surround numbers of an n X 2 rectangle when n is odd. 1

%I

%S 83,361,951,1997,3667,6153,9671,14461,20787,28937,39223,51981,67571,

%T 86377,108807,135293,166291,202281,243767,291277,345363,406601,475591,

%U 552957,639347,735433,841911,959501,1088947,1231017,1386503,1556221

%N Surround numbers of an n X 2 rectangle when n is odd.

%C See A061524 for even n.

%H E. J. Friedman, <a href="https://erich-friedman.github.io/mathmagic/0599.html">Math. Magic: May, 1999</a>

%F a(n) = (n^4 + 32n^3 + 278n^2 + 656n + 361)/16 when n is odd.

%F From _Chai Wah Wu_, Dec 20 2019: (Start)

%F a(n) = 5*a(n-1) - 10*a(n-2) + 10*a(n-3) - 5*a(n-4) + a(n-5) for n > 5.

%F G.f.: x*(3*x^4 - 22*x^3 + 24*x^2 + 54*x - 83)/(x - 1)^5. (End)

%Y Cf. A047875 A061524.

%K easy,nonn

%O 1,1

%A _Jason Earls_, May 03 2001

%E More terms from Larry Reeves (larryr(AT)acm.org), May 07 2001

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Last modified August 1 10:37 EDT 2021. Contains 346385 sequences. (Running on oeis4.)