The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Please make a donation to keep the OEIS running. We are now in our 56th year. In the past year we added 10000 new sequences and reached almost 9000 citations (which often say "discovered thanks to the OEIS"). Other ways to donate

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A137280 a(n) = 3*a(n-1) + 7*a(n-2). 0
 1, 10, 37, 181, 802, 3673, 16633, 75610, 343261, 1559053, 7079986, 32153329, 146019889, 663132970, 3011538133, 13676545189, 62110402498, 282067023817, 1280973888937, 5817390833530, 26418989723149, 119978705004157 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS a(n) == 1 mod 9. a(n)/a(n-1) tends to 4.54138126... = (3 + sqrt(37))/2 LINKS Index entries for linear recurrences with constant coefficients, signature (3,7) FORMULA a(1) = 1, a(2) = 10, a(n), n>2 = 3*a(n-1) + 7*a(n-2). a(n) = upper left term in [1,3; 3,2]^n O.g.f.: x*(1+7*x)/(1-3*x-7*x^2) . a(n)=A015524(n)+7*A015524(n-1). - R. J. Mathar, Mar 17 2008 a(n)=-17/74*(3/2-1/2*sqrt(37))^n*sqrt(37)+1/2*(3/2-1/2*sqrt(37))^n+17/74*sqrt(37)*(3 /2+1/2*sqrt(37))^n+1/2*(3/2+1/2*sqrt(37))^n, with n>=0 - Paolo P. Lava, Jun 03 2008 EXAMPLE a(4) = 181 = 3*a(3) + 7*a(2) = 3*37 + 7*10. a(4) = 181 = upper left term in [1,3; 3,2]^4. CROSSREFS Sequence in context: A199208 A110528 A208674 * A071261 A129426 A215881 Adjacent sequences:  A137277 A137278 A137279 * A137281 A137282 A137283 KEYWORD nonn,easy AUTHOR Gary W. Adamson, Mar 14 2008 STATUS approved

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

Last modified November 24 07:14 EST 2020. Contains 338607 sequences. (Running on oeis4.)