This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A128076 A128064 * A004736. 4
 1, 3, 2, 5, 4, 3, 7, 6, 5, 4, 9, 8, 7, 6, 5, 11, 10, 9, 8, 7, 6, 13, 12, 11, 10, 9, 8, 7, 15, 14, 13, 12, 11, 10, 9, 8, 17, 16, 15, 14, 13, 12, 11, 10, 9, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10 (list; table; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Row sums = the pentagonal numbers, A000316, starting (1, 5, 12, 22, 35, 51,...). A004736 = (1; 2, 1; 3, 2, 1;...). From Boris Putievskiy, Jan 24 2013: (Start) Table T(n,k)=n+2*k-2 n, k > 0, read by antidiagonals. General case A209304. Let m be natural number. The first column of the table T(n,1) is the sequence of the natural numbers A000027. Every next column is formed from previous shifted by m elements. For m=0 the result is A002260, for m=1 the result is A002024, for m=2 the result is A128076, for m=3 the result is A131914, for m=4 the result is A209304. (End) LINKS Boris Putievskiy, Transformations [Of] Integer Sequences And Pairing Functions, arXiv preprint arXiv:1212.2732, 2012. FORMULA A128064 * A004736 as infinite lower triangular matrices. From Boris Putievskiy, Jan 24 2013: (Start) For the general case a(n) = m*A003056 -(m-1)*A002260. a(n) = m*(t+1) + (m-1)*(t*(t+1)/2-n), where t=floor((-1+sqrt(8*n-7))/2). For m = 2 a(n) = 2*A003056 -A002260. a(n) = 2*(t+1)+(t*(t+1)/2-n), where t=floor((-1+sqrt(8*n-7))/2). (End) EXAMPLE First few rows of the triangle are: 1; 3, 2; 5, 4, 3; 7, 6, 5, 4; 9, 8, 7, 6, 5; ... CROSSREFS Cf. A128064, A004736, A000326, A003056, A002260, A002024,  A131914, A209304. Sequence in context: A205850 A204890 A239680 * A076243 A140061 A292776 Adjacent sequences:  A128073 A128074 A128075 * A128077 A128078 A128079 KEYWORD nonn,tabl AUTHOR Gary W. Adamson, Feb 14 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 April 19 11:17 EDT 2019. Contains 322264 sequences. (Running on oeis4.)