A142248 Odd numbers in A138123.

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

Links

Table of n, a(n) for n=1..40.

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

Cf. A000204, A138123.

Sequence in context: A106967 A045420 A190898 * A045421 A072456 A138659

Adjacent sequences: A142245 A142246 A142247 * A142249 A142250 A142251

Keyword

nonn,changed

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