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

 Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 59th year, we have over 358,000 sequences, and we’ve crossed 10,300 citations (which often say “discovered thanks to the OEIS”). Other ways to Give
 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A154325 Triangle with interior all 2's and borders 1. 7
 1, 1, 1, 1, 2, 1, 1, 2, 2, 1, 1, 2, 2, 2, 1, 1, 2, 2, 2, 2, 1, 1, 2, 2, 2, 2, 2, 1, 1, 2, 2, 2, 2, 2, 2, 1, 1, 2, 2, 2, 2, 2, 2, 2, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 1 (list; table; graph; refs; listen; history; text; internal format)
 OFFSET 0,5 COMMENTS This triangle follows a general construction method as follows: Let a(n) be an integer sequence with a(0)=1, a(1)=1. Then T(n,k,r):=[k<=n](1+r*a(k)*a(n-k)) defines a symmetrical triangle. Row sums are n + 1 + r*Sum_{k=0..n} a(k)*a(n-k) and central coefficients are 1+r*a(n)^2. Here a(n)=1-0^n and r=1. Row sums are A004277. Eigensequence of the triangle = A000129, the Pell sequence. - Gary W. Adamson, Feb 12 2009 Inverse has general element T(n,k)*(-1)^(n-k). - Paul Barry, Oct 06 2010 LINKS FORMULA Number triangle T(n,k) = [k<=n](2-0^(n-k)-0^k+0^(n+k))=[k<=n](2-0^(k(n-k))). a(n) = 2 - A103451(n). - Omar E. Pol, Jan 18 2009 EXAMPLE Triangle begins 1; 1, 1; 1, 2, 1; 1, 2, 2, 1; 1, 2, 2, 2, 1; 1, 2, 2, 2, 2, 1; 1, 2, 2, 2, 2, 2, 1; From Paul Barry, Oct 06 2010: (Start) Production matrix is 1, 1; 0, 1, 1; 0, -1, 0, 1; 0, 1, 0, 0, 1; 0, -1, 0, 0, 0, 1; 0, 1, 0, 0, 0, 0, 1; 0, -1, 0, 0, 0, 0, 0, 1; 0, 1, 0, 0, 0, 0, 0, 0, 1; (End) CROSSREFS Cf. A129765. - R. J. Mathar, Jan 14 2009 Cf. A103451. - Omar E. Pol, Jan 18 2009 Cf. A000129. - Gary W. Adamson, Feb 12 2009 Sequence in context: A134034 A174886 A157415 * A129765 A143187 A348042 Adjacent sequences: A154322 A154323 A154324 * A154326 A154327 A154328 KEYWORD easy,nonn,tabl AUTHOR Paul Barry, Jan 07 2009 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.

Last modified December 3 09:50 EST 2022. Contains 358517 sequences. (Running on oeis4.)