A118831 -id:A118831 - cp's OEIS frontend

A107850 Expansion of g.f. (x^2+x+1)(2x^2+2x+1)(x-1)^2/((1-x^2-2x^3)(x^4+1)).

1, 1, 1, 0, 1, 1, 3, 6, 7, 13, 17, 24, 41, 57, 91, 142, 207, 325, 489, 736, 1137, 1713, 2611, 3990, 6039, 9213, 14017, 21288, 32441, 49321, 75019, 114206, 173663, 264245, 402073, 611568, 930561, 1415713, 2153699, 3276838, 4985127, 7584237, 11538801

Offset: 0

Creighton Dement, May 25 2005

Floretion Algebra Multiplication Program, FAMP Code: 1lesforzapseq[(.5i' + .5j' + .5'ki' + .5'kj')*(.5'i + .5'j + .5'ik' + .5'jk')], 1vesforzap = A000004

Harvey P. Dale, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (0,1,2,-1,0,1,2).

Cf. A107849, A107851, A107852.

CoefficientList[Series[(x^2+x+1)(2x^2+2x+1)(x-1)^2/((1-x^2-2x^3)(x^4+1)),{x,0,50}],x] (* or *) LinearRecurrence[{0,1,2,-1,0,1,2},{1,1,1,0,1,1,3},50] (* Harvey P. Dale, Dec 26 2015 *)

a(n) = A052947(n-1)+A118831(n+6). - R. J. Mathar, Apr 18 2008

a(0)=1, a(1)=1, a(2)=1, a(3)=0, a(4)=1, a(5)=1, a(6)=3, a(n)=a(n-2)+ 2*a(n-3)- a(n-4)+a(n-6)+2*a(n-7). - Harvey P. Dale, Dec 26 2015

A118830 2-adic continued fraction of zero, where a(n) = -1 if n is odd, 2*A006519(n/2) otherwise.

Original entry on oeis.org

-1, 2, -1, 4, -1, 2, -1, 8, -1, 2, -1, 4, -1, 2, -1, 16, -1, 2, -1, 4, -1, 2, -1, 8, -1, 2, -1, 4, -1, 2, -1, 32, -1, 2, -1, 4, -1, 2, -1, 8, -1, 2, -1, 4, -1, 2, -1, 16, -1, 2, -1, 4, -1, 2, -1, 8, -1, 2, -1, 4, -1, 2, -1, 64, -1, 2, -1, 4, -1, 2, -1, 8, -1, 2, -1, 4, -1, 2, -1, 16, -1, 2, -1, 4, -1, 2, -1, 8, -1, 2, -1, 4, -1, 2, -1, 32, -1, 2, -1

Offset: 1

Paul D. Hanna, May 01 2006

Limit of convergents equals zero; only the 6th convergent is indeterminate. Other 2-adic continued fractions of zero are: A118821, A118824, A118827. A006519(n) is the highest power of 2 dividing n; A080277 = partial sums of A038712, where A038712(n) = 2*A006519(n) - 1.

			For n >= 1, convergents A118831(k)/A118832(k):
  at k = 4*n: 1/(2*A080277(n));
  at k = 4*n+1: 1/(2*A080277(n)-1);
  at k = 4*n+2: 1/(2*A080277(n)-2);
  at k = 4*n-1: 0.
Convergents begin:
  -1/1, -1/2, 0/-1, -1/-2, 1/1, 1/0, 0/1, 1/8,
  -1/-7, -1/-6, 0/-1, -1/-10, 1/9, 1/8, 0/1, 1/24,
  -1/-23, -1/-22, 0/-1, -1/-26, 1/25, 1/24, 0/1, 1/32,
  -1/-31, -1/-30, 0/-1, -1/-34, 1/33, 1/32, 0/1, 1/64, ...

Antti Karttunen, Table of n, a(n) for n = 1..65537

Cf. A006519, A080277; convergents: A118831/A118832; variants: A118821, A118824, A118827; A100338.

Array[If[OddQ@ #, -1, 2^IntegerExponent[#, 2]] &, 99] (* Michael De Vlieger, Nov 06 2018 *)

a(n)=local(p=-1,q=+2);if(n%2==1,p,q*2^valuation(n/2,2))

A118832 Denominators of the convergents of the 2-adic continued fraction of zero given by A118830.

Original entry on oeis.org

1, 2, -1, -2, 1, 0, 1, 8, -7, -6, -1, -10, 9, 8, 1, 24, -23, -22, -1, -26, 25, 24, 1, 32, -31, -30, -1, -34, 33, 32, 1, 64, -63, -62, -1, -66, 65, 64, 1, 72, -71, -70, -1, -74, 73, 72, 1, 88, -87, -86, -1, -90, 89, 88, 1, 96, -95, -94, -1, -98, 97, 96, 1, 160, -159, -158, -1, -162, 161, 160, 1, 168, -167, -166, -1, -170, 169, 168

Offset: 1

Paul D. Hanna, May 01 2006

			For n>=1, convergents A118831(k)/A118832(k) are:
at k = 4*n: 1/(2*A080277(n));
at k = 4*n+1: 1/(2*A080277(n)-1);
at k = 4*n+2: 1/(2*A080277(n)-2);
at k = 4*n-1: 0.
Convergents begin:
-1/1, -1/2, 0/-1, -1/-2, 1/1, 1/0, 0/1, 1/8,
-1/-7, -1/-6, 0/-1, -1/-10, 1/9, 1/8, 0/1, 1/24,
-1/-23, -1/-22, 0/-1, -1/-26, 1/25, 1/24, 0/1, 1/32,
-1/-31, -1/-30, 0/-1, -1/-34, 1/33, 1/32, 0/1, 1/64, ...

Cf. A080277; A118830 (partial quotients), A118831 (numerators).

{a(n)=local(p=-1,q=+2,v=vector(n,i,if(i%2==1,p,q*2^valuation(i/2,2)))); contfracpnqn(v)[2,1]}

a(4*n) = (-1)^n*2*A080277(n); a(4*n+1) = -(-1)^n*(2*A080277(n)-1); a(4*n+2) = -(-1)^n*(2*A080277(n)-2); a(4*n-1) = (-1)^n.

cp's OEIS Frontend

A107850 Expansion of g.f. (x^2+x+1)(2x^2+2x+1)(x-1)^2/((1-x^2-2x^3)(x^4+1)).

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A118830 2-adic continued fraction of zero, where a(n) = -1 if n is odd, 2*A006519(n/2) otherwise.

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A118832 Denominators of the convergents of the 2-adic continued fraction of zero given by A118830.

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cp's OEIS Frontend

A107850 Expansion of g.f. (x^2+x+1)*(2*x^2+2*x+1)*(x-1)^2/((1-x^2-2*x^3)*(x^4+1)).

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A118830 2-adic continued fraction of zero, where a(n) = -1 if n is odd, 2*A006519(n/2) otherwise.

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A118832 Denominators of the convergents of the 2-adic continued fraction of zero given by A118830.

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PARI

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A107850 Expansion of g.f. (x^2+x+1)(2x^2+2x+1)(x-1)^2/((1-x^2-2x^3)(x^4+1)).