A376901 a(n) = (n*(n-1)+(-1)^n+5)/2.
3, 2, 4, 5, 9, 12, 18, 23, 31, 38, 48, 57, 69, 80, 94, 107, 123, 138, 156, 173, 193, 212, 234, 255, 279, 302, 328, 353, 381, 408, 438, 467, 499, 530, 564, 597, 633, 668, 706, 743, 783, 822, 864, 905, 949, 992, 1038, 1083, 1131, 1178, 1228, 1277, 1329, 1380, 1434
Offset: 0
Links
- Eric Weisstein's World of Mathematics, Disorder Number.
- Eric Weisstein's World of Mathematics, Pan Graph.
- Index entries for linear recurrences with constant coefficients, signature (2,0,-2,1).
Programs
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Mathematica
Table[(n (n - 1) + 5 + (-1)^n)/2, {n, 20}] LinearRecurrence[{2, 0, -2, 1}, {2, 4, 5, 9}, {0, 20}]
Formula
a(n) = 2*a(n-1)-2*a(n-3)+1*a(n-4).
G.f.: x*(-2+3*x^2-3*x^3)/((-1+x)^3*(1+x)).
After initial terms same as {A114113}+2, {A236453}+1, ({A081353}+1)/2 + 2. Hugo Pfoertner, Oct 10 2024.
Comments