This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A090752 Number of compositions (ordered partitions) of n whereby at most 1 increase is allowed and this increase must be by 1. 0
 1, 2, 4, 7, 13, 21, 36, 56, 89, 134, 204, 296, 435, 618, 879, 1223, 1702, 2323, 3171, 4263, 5720, 7589, 10043, 13158, 17202, 22305, 28839, 37038, 47437, 60391, 76686, 96872, 122047, 153081, 191513, 238625, 296620, 367379, 453948, 559112, 687107 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Number of compositions of n in which exactly 1 increase is allowed and this increase must be by 1, is a(n)-A000041(n). - Vladeta Jovovic, Feb 09 2004 LINKS EXAMPLE a(5)=13, as we have 5, 41, 32, 23, 311, 221, 212, 122, 2111, 1211, 1121, 1112 and 11111. PROG (PARI) Ta = matrix(70, 70, i, j, -1); Tn = Ta; doAllowed(last, left) = local(c); c = Ta[last, left]; if (c == -1, c = 0; for (i = 1, min(last, left), c += b(i, left - i, 1)); c += b(last + 1, left - last - 1, 0); Ta[last, left] = c); c; doNot(last, left) = local(c); c = Tn[last, left]; if (c == -1, c = 0; for (i = 1, min(last, left), c += b(i, left - i, 0)); Tn[last, left] = c); c; b(last, left, allowed) = if (left == 0, return(1)); if (left < 0, return(0)); if (allowed, doAllowed(last, left), doNot(last, left)); a(n) = sum (i = 1, n, b(i, n - i, 1)); (Wasserman) CROSSREFS Cf. A034297, A003116. Sequence in context: A037032 A165753 A205183 * A051058 A026625 A026691 Adjacent sequences:  A090749 A090750 A090751 * A090753 A090754 A090755 KEYWORD nonn,changed AUTHOR Jon Perry, Feb 06 2004 EXTENSIONS More terms from Vladeta Jovovic, Feb 13 2004 More terms from David Wasserman, Feb 02 2006 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Transforms | Puzzles | Hot | Classics
Recent Additions | More pages | Superseeker | Maintained by The OEIS Foundation Inc.

Content is available under The OEIS End-User License Agreement .

Last modified May 21 10:03 EDT 2013. Contains 225478 sequences.