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!)
A114698 Let M(n) be the n X n matrix m(i,j)=min(i,j) for 1<=i,j<=n then a(n) is the trace of M(n)^(-3). 2
1, 18, 38, 58, 78, 98, 118, 138, 158, 178, 198, 218, 238, 258, 278, 298, 318, 338, 358, 378, 398, 418, 438, 458, 478, 498, 518, 538, 558, 578, 598, 618, 638, 658, 678, 698, 718, 738, 758, 778, 798, 818, 838, 858, 878, 898, 918, 938, 958, 978, 998, 1018, 1038 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
More generally for any n>=floor((m+1)/2) the trace of M(n)^(-m) = binomial(2*m,m)*n-2^(2*m-1)+binomial(2*m-1,m).
LINKS
S. Barbero, Dickson Polynomials, Chebyshev Polynomials, and Some Conjectures of Jeffery, Journal of Integer Sequences, 17 (2014), #14.3.8.
FORMULA
a(1)=1 then a(n)=20n-22.
(Conjecture) G.f.: F(x)=(1+16*x+3*x^2)/(1-x)^2. - L. Edson Jeffery, Jan 21 2012
(Conjecture) a(n)=2*a(n-1)-a(n-2), n>1, a(0)=1, a(1)=18. - L. Edson Jeffery, Jan 21 2012
PROG
(PARI) a(n)=if(n<2, 1, 20*n-22)
CROSSREFS
Sequence in context: A041644 A041646 A244412 * A119127 A190739 A084585
KEYWORD
nonn
AUTHOR
Benoit Cloitre, Feb 09 2006
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 March 29 09:59 EDT 2024. Contains 371268 sequences. (Running on oeis4.)