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A142248
Odd numbers in A138123.
0
1, 3, 7, 11, 17, 29, 47, 75, 123, 199, 321, 521, 843, 1363, 2207, 3571, 5777, 9349, 15127, 24475, 39603, 64079, 103681, 167761, 271443, 439203, 710647, 1149851, 1860497, 3010349, 4870847, 7881195, 12752043, 20633239, 33385281, 54018521, 87403803, 141422323, 228826127, 370248451
OFFSET
1,2
FORMULA
Conjectures from Chai Wah Wu, Apr 15 2024: (Start)
a(n) = a(n-1) + a(n-2) + a(n-3) - a(n-4) - a(n-5) for n > 6.
G.f.: x*(-2*x^5 - 3*x^4 + 3*x^2 + 2*x + 1)/((x - 1)*(x^2 + x - 1)*(x^2 + x + 1)). (End)
PROG
(PARI) L(n) = fibonacci(n+1)+fibonacci(n-1); \\ A000204
T(n, k) = if (k<n, return(0)); if (n==k, return(L(n))); if (k==2*n, return((-1)^(n+1))); return(0); \\ A138123
lista(nn) = my(list = List()); for (k=1, nn, my(i=k, j=1, s=0); for (m=1, k, s += T(i, j); i--; j++; ); if ((s>0) && (s%2), listput(list, s)); ); Set(list);
CROSSREFS
Sequence in context: A106967 A045420 A190898 * A045421 A072456 A138659
KEYWORD
nonn
AUTHOR
Paul Curtz, Sep 18 2008
EXTENSIONS
Edited by N. J. A. Sloane, Dec 10 2008
More terms from Michel Marcus, Apr 16 2024
STATUS
approved