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A122461 Repetitions of even numbers four times. 1
0, 0, 0, 0, 2, 2, 2, 2, 4, 4, 4, 4, 6, 6, 6, 6, 8, 8, 8, 8, 10, 10, 10, 10, 12, 12, 12, 12, 14, 14, 14, 14, 16, 16, 16, 16, 18, 18, 18, 18, 20, 20, 20, 20, 22, 22, 22, 22, 24, 24, 24, 24, 26, 26, 26, 26, 28, 28, 28, 28, 30, 30, 30, 30, 32, 32, 32, 32, 34, 34, 34, 34, 36, 36, 36, 36 (list; graph; refs; listen; history; internal format)
OFFSET

0,5

FORMULA

a(n) = {Sum_{k=0..n} (k+1)*cos[(n-k)*Pi/2]}+1/4*[2*cos(n*Pi/2)+1+(-1)^n]-2, with n>=0 - Paolo P. Lava (paoloplava(AT)gmail.com), May 15 2007

a(n)= 2*A002265(n) = 2*A180969(2,n). [Adriano Caroli Nov 25 2010, corrected by R. J. Mathar, Nov 26 2010]

CROSSREFS

Cf. A092533.

Sequence in context: A072376 A131883 A113452 * A092533 A092532 A073504

Adjacent sequences:  A122458 A122459 A122460 * A122462 A122463 A122464

KEYWORD

nonn

AUTHOR

Paolo P. Lava & Giorgio Balzarotti (paoloplava(AT)gmail.com), Oct 20 2006

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Last modified February 16 02:51 EST 2012. Contains 205860 sequences.