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 | | In general a(n,m)=2^n/m*Sum(k,0,m-1,Cos(4Pi*k/m)Cos(2Pi*k/m)^n) is the number of walks of length n between two vertices at distance 2 in the cycle graph C_m. |
 | | This sequence is not the better-known generalized Lucas numbers V(n,a,b) defined for fixed integers a and b such that D = a^2 + 4*b is nonnegative, V(0) = 2, V(1) = a, and for n>1 the recurrence V(n) = V(n-1) + V(n-2). |
 | | (given by A027423, number of positive divisors of n!) %C A079197 First four rows: 0; 0,1; 1,4,5,107; 0,0,0,5,0,28,488,43389 %C A079197 A079195(x) is equal to the sum of the products of each element in row x of this sequence and the corresponding element of A079210. |
| www.research.att.com /~njas/sequences/eisBTfry00059.txt (3773 words) |
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