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Search: id:A134455
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| A134455 |
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a(0) = a(1) = 1, a(2) = 2; a(n) = 2*a(n-2) + a(n-1)*a(n-3) |
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+0
1
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| 1, 1, 2, 4, 7, 16, 49, 375, 6098, 299552, 112344196, 685075506312, 205215738291460616, 23054797124901926721197360
(list; graph; listen)
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OFFSET
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0,3
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COMMENT
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This is a recurrence relation which has 1,1 and 2 as the base cases and the nth term is obtained by multiplying the (n-2)th term by 2 and adding it with the product of (n-1)th and (n-3)rd term.
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EXAMPLE
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f(5) = 2*f(3)+ f(4)*f(2) = 2*4 + 7*2 = 22
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PROGRAM
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Formula for calculating the nth term : int n; int val; int seq(int n) { if( n==0 || n==1 ) { seq(0) = seq(1) = 1; } else if( n==2 ) { seq(2) = 2; } else { val = 2*seq(n-2) + seq(n-1)*seq(n-3); } return val ; }
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CROSSREFS
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Adjacent sequences: A134452 A134453 A134454 this_sequence A134456 A134457 A134458
Sequence in context: A151378 A137568 A010355 this_sequence A113878 A026775 A027238
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KEYWORD
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easy,nonn
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AUTHOR
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Mohit Maheshwari (mohitmahe1989(AT)gmail.com), Jan 19 2008
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