login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A125662 A convolution triangle of numbers based on A001906 (even indexed Fibonacci numbers). 8
1, 3, 1, 8, 6, 1, 21, 25, 9, 1, 55, 90, 51, 12, 1, 144, 300, 234, 86, 15, 1, 377, 954, 951, 480, 130, 18, 1, 987, 2939, 3573, 2305, 855, 183, 21, 1, 2584, 8850, 12707, 10008, 4740, 1386, 245, 24, 1, 6765, 26195, 43398, 40426, 23373, 8715, 2100, 316, 27, 1 (list; table; graph; refs; listen; history; text; internal format)
OFFSET
0,2
COMMENTS
Subtriangle of the triangle given by [0,3,-1/3,1/3,0,0,0,0,0,...] DELTA [1,0,0,0,0,0,...] where DELTA is the operator defined in A084938. Unsigned version of A123965 and A124025.
Riordan array (1/(1-3*x+x^2), x/(1-3*x+x^2)). - Philippe Deléham, Feb 19 2012
A125662 = A078812*A007318 as infinite lower triangular matrices. - Philippe Deléham, Feb 19 2012
Triangle of coefficients of Chebyshev's S(n,x+3) polynomials (exponents of x in increasing order). - Philippe Deléham, Feb 19 2012
For 1<=k<=n, T(n,k) equals the number of (n-1)-length words over {0,1,2,3} containing k-1 letters equal 3 and avoiding 01. - Milan Janjic, Dec 20 2016
LINKS
Michael De Vlieger, Table of n, a(n) for n = 0..11475 (rows 0 <= n <= 150)
Milan Janjić, Words and Linear Recurrences, J. Int. Seq. 21 (2018), #18.1.4.
FORMULA
T(n,k) = T(n-1,k-1) + 3*T(n-1,k) - T(n-2,k) ; T(0,0)=1 ; T(n,k)=0 if k<0 or if k>n.
G.f.: 1/(1-3*x+x^2-y*x). - Philippe Deléham, Feb 19 2012
EXAMPLE
Triangle begins:
1;
3, 1;
8, 6, 1;
21, 25, 9, 1;
55, 90, 51, 12, 1;
Triangle [0,3,-1/3,1/3,0,0,0,...] DELTA [1,0,0,0,0,0,...]begins:
1;
0, 1;
0, 3, 1;
0, 8, 6, 1;
0, 21, 25, 9, 1;
0, 55, 90, 51, 12, 1;
MATHEMATICA
With[{n = 9}, DeleteCases[#, 0] & /@ CoefficientList[Series[1/(1 - 3 x + x^2 - y x), {x, 0, n}, {y, 0, n}], {x, y}]] // Flatten (* Michael De Vlieger, Apr 25 2018 *)
CROSSREFS
Cf. Diagonal sums: A000244(powers of 3); Row sums: A001353 (n+1); Diagonals: A001906(n+1), A001871; A000012, A008585, A062728.
Cf. Triangle of coefficients of Chebyshev's S(n,x+k) polynomials: A207824, A207823, A125662, A078812, A101950, A049310, A104562, A053122, A207815, A159764, A123967 for k = 5, 4, 3, 2, 1, 0, -1, -2, -3, -4, -5 respectively.
Sequence in context: A103247 A030523 A207815 * A123965 A124025 A257488
KEYWORD
easy,nonn,tabl
AUTHOR
Philippe Deléham, Jan 28 2007
EXTENSIONS
a(45) corrected and a(51) added by Philippe Deléham, Feb 19 2012
STATUS
approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified June 2 13:38 EDT 2023. Contains 363097 sequences. (Running on oeis4.)