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Search: id:A126560
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| A126560 |
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GCD[4(n+1)(n+2),n(n+3)]. |
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+0
1
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| 4, 2, 2, 4, 8, 2, 2, 8, 4, 2, 2, 4, 8, 2, 2, 8, 4, 2, 2, 4, 8, 2, 2, 8, 4, 2, 2, 4, 8, 2, 2, 8, 4, 2, 2, 4, 8, 2, 2, 8, 4, 2, 2, 4, 8, 2, 2, 8
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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a(n) = n*(3 + n)/A125650(n). Sequence is periodic with cycle 4,2,2,4,8,2,2,8.
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FORMULA
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a(n) = GCD[4(n+1)(n+2),n(n+3)]
a(n)=(1/28)*{18*[n mod 8]-17*[(n+1) mod 8]+4*[(n+2) mod 8]+25*[(n+3) mod 8]-10*[(n+4) mod 8]-3*[(n+5) mod 8]+4*[(n+6) mod 8]+11*[(n+7) mod 8]}, with n>=0. - Paolo P. Lava (ppl(AT)spl.at), Jun 01 2007
a(n)=4+(-1+1/2*2^(1/2))*cos(Pi*n/4)-1/2*2^(1/2)*sin(Pi*n/4)+(-1/2*2^(1/2)-1)*cos(3*Pi*n/4)-1/2*2^(1/2)*sin(3*Pi*n/4)+2*cos(n*Pi/2)-2*sin(n*Pi/2) [From Richard Choulet (richardchoulet(AT)yahoo.fr), Dec 11 2008]
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MATHEMATICA
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Table[GCD[m(3+m), 4(1+m)(2+m)], {m, 48}]
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CROSSREFS
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Cf. A125650.
Sequence in context: A141035 A100854 A021707 this_sequence A064213 A016510 A023634
Adjacent sequences: A126557 A126558 A126559 this_sequence A126561 A126562 A126563
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KEYWORD
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nonn
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AUTHOR
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Zak Seidov (zakseidov(AT)yahoo.com), Mar 12 2007
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