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Search: id:A131806
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A131806 Period 4: repeat 0,2,4,6. +0
1
0, 2, 4, 6, 0, 2, 4, 6, 0, 2, 4, 6, 0, 2, 4, 6, 0, 2, 4, 6, 0, 2, 4, 6, 0, 2, 4, 6, 0, 2, 4, 6, 0, 2, 4, 6, 0, 2, 4, 6, 0, 2, 4, 6, 0, 2, 4, 6, 0, 2, 4, 6, 0, 2, 4, 6, 0, 2, 4, 6, 0, 2, 4, 6, 0, 2, 4, 6, 0, 2, 4, 6, 0, 2, 4, 6, 0, 2, 4, 6, 0, 2, 4, 6, 0, 2, 4, 6, 0, 2, 4, 6, 0, 2, 4, 6, 0, 2, 4, 6, 0, 2, 4, 6, 0, 2, 4, 6 (list; graph; listen)
OFFSET

1,2

LINKS

Salvatore Gambino, Terne pitagoriche primitive

FORMULA

a(n) = 3+(-1)^n+2*(-1)^((2*n+1-(-1)^n)/4)

O.g.f.: -2x^2(1+2x+3x^2)/((x-1)(x+1)(x^2+1)) . a(n) = 2*A010873(n-1). - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jan 15 2008

a(n)=2*(n mod 4), with n>=0 - Paolo P. Lava (ppl(AT)spl.at), Jan 28 2008

a(n)=3-(1-I)*I^n-(-1)^n-(1+I)*(-I)^n, with n>=0 and I=sqrt(-1) - Paolo P. Lava (ppl(AT)spl.at), Jul 17 2008

CROSSREFS

Sequence in context: A056683 A066684 A128124 this_sequence A004518 A013670 A121206

Adjacent sequences: A131803 A131804 A131805 this_sequence A131807 A131808 A131809

KEYWORD

nonn,easy

AUTHOR

Salvatore Gambino (salvatore.gambino(AT)fastwebnet.it), Oct 04 2007

EXTENSIONS

More terms from R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jan 15 2008

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Last modified August 29 17:54 EDT 2008. Contains 143238 sequences.


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