This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A133602 The matrix-vector product A133080 * A000108. 1
 1, 2, 2, 7, 14, 56, 132, 561, 1430, 6292, 16796, 75582, 208012, 950912, 2674440, 12369285, 35357670, 165002460, 477638700, 2244901890, 6564120420, 31030387440, 91482563640, 434542177290, 1289904147324, 6151850548776 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS A133603 is a companion sequence. LINKS FORMULA A133080 * A000108, where A133080 = an infinite lower triangular matrix and A000108 = the Catalan sequence as a vector. a(2n) = A048990(n). a(2n+1) = A005807(2n). Conjecture: n*(n-1)*(n-3)*(3*n-4)*a(n) -8*(n-1)*(2*n-5)*a(n-1) -4*(n-2)*(3*n-1)*(2*n-5)*(2*n-7)*a(n-2)=0. - R. J. Mathar, Jun 20 2015 EXAMPLE a(4) = C(4) = 14. a(5) = 56 = C(5) + C(4) = 42 + 14. PROG (Python) from sympy import catalan def a005807(n): return catalan(n) + catalan(n + 1) def a048990(n): return catalan(2*n) l=[1, 2] for n in xrange(2, 31): l+=[a048990(n/2) if n%2==0 else a005807(n - 1)] print l # Indranil Ghosh, Jul 15 2017 CROSSREFS Cf. A097806, A133080, A000108, A133603. Sequence in context: A061575 A306009 A290646 * A137249 A216461 A238833 Adjacent sequences:  A133599 A133600 A133601 * A133603 A133604 A133605 KEYWORD nonn,easy AUTHOR Gary W. Adamson, Sep 18 2007 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 September 15 20:41 EDT 2019. Contains 327087 sequences. (Running on oeis4.)