This site is supported by donations to The OEIS Foundation.

 Annual Appeal: Please make a donation to keep the OEIS running. In 2018 we replaced the server with a faster one, added 20000 new sequences, and reached 7000 citations (often saying "discovered thanks to the OEIS"). Other ways to donate

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A191453 Dispersion of (2*floor(3n/2)), by antidiagonals. 1
 1, 2, 3, 6, 8, 4, 18, 24, 12, 5, 54, 72, 36, 14, 7, 162, 216, 108, 42, 20, 9, 486, 648, 324, 126, 60, 26, 10, 1458, 1944, 972, 378, 180, 78, 30, 11, 4374, 5832, 2916, 1134, 540, 234, 90, 32, 13, 13122, 17496, 8748, 3402, 1620, 702, 270, 96, 38, 15, 39366 (list; table; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Background discussion:  Suppose that s is an increasing sequence of positive integers, that the complement t of s is infinite, and that t(1)=1.  The dispersion of s is the array D whose n-th row is (t(n), s(t(n)), s(s(t(n)), s(s(s(t(n)))), ...).  Every positive integer occurs exactly once in D, so that, as a sequence, D is a permutation of the positive integers.  The sequence u given by u(n)=(number of the row of D that contains n) is a fractal sequence.  Examples: (1) s=A000040 (the primes), D=A114537, u=A114538. (2) s=A022343 (without initial 0), D=A035513 (Wythoff array), u=A003603. (3) s=A007067, D=A035506 (Stolarsky array), u=A133299. More recent examples of dispersions: A191426-A191455. LINKS EXAMPLE Northwest corner: 1...2....6....18...54 3...8....24...72...216 4...12...36...108..324 5...14...42...126..378 7...20...60...180..540 MATHEMATICA (* Program generates the dispersion array T of increasing sequence f[n] *) r=40; r1=12; c=40; c1=12; f[n_] :=2Floor[3n/2]   (* complement of column 1 *) mex[list_] := NestWhile[#1 + 1 &, 1, Union[list][[#1]] <= #1 &, 1, Length[Union[list]]] rows = {NestList[f, 1, c]}; Do[rows = Append[rows, NestList[f, mex[Flatten[rows]], r]], {r}]; t[i_, j_] := rows[[i, j]]; TableForm[Table[t[i, j], {i, 1, 10}, {j, 1, 10}]] (* A191453 array *) Flatten[Table[t[k, n - k + 1], {n, 1, c1}, {k, 1, n}]] (* A191453 sequence *) (* Program by Peter J. C. Moses, Jun 01 2011 *) CROSSREFS Cf. A114537, A035513, A035506. Sequence in context: A265297 A140266 A140265 * A191454 A276955 A276945 Adjacent sequences:  A191450 A191451 A191452 * A191454 A191455 A191456 KEYWORD nonn,tabl AUTHOR Clark Kimberling, Jun 05 2011 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 December 15 22:36 EST 2018. Contains 318155 sequences. (Running on oeis4.)