login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo

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 56th year, we are closing in on 350,000 sequences, and we’ve crossed 9,700 citations (which often say “discovered thanks to the OEIS”).

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A130830 Irregular triangle read by rows: row(1) = [1,2,3]; thereafter row(n+1) is the tensor square of row(n). 1
1, 2, 3, 1, 2, 3, 2, 4, 6, 3, 6, 9, 1, 2, 3, 2, 4, 6, 3, 6, 9, 2, 4, 6, 4, 8, 12, 6, 12, 18, 3, 6, 9, 6, 12, 18, 9, 18, 27, 2, 4, 6, 4, 8, 12, 6, 12, 18, 4, 8, 12, 8, 16, 24, 12, 24, 36, 6, 12, 18, 12, 24, 36, 18, 36, 54, 3, 6, 9, 6, 12, 18, 9, 18, 27, 6, 12, 18, 12, 24, 36, 18, 36, 54, 9, 18, 27 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Self-similar recursion based on number set {1,2,3}.

Row lengths are A011764.

LINKS

Table of n, a(n) for n=1..87.

FORMULA

It appears that a(n) = A006047(n-12) for n >= 13. - Michel Marcus, Oct 24 2017

EXAMPLE

Triangle begins:

{1, 2, 3},

{1, 2, 3, 2, 4, 6, 3, 6, 9},

{1, 2, 3, 2, 4, 6, 3, 6, 9, 2, 4, 6, 4, 8, 12, 6, 12, 18, 3, 6, 9, 6, 12, 18, 9, 18, 27, 2, 4, 6, 4, 8, 12, 6, 12, 18, 4, 8, 12, 8, 16, 24, 12, 24, 36, 6, 12, 18, 12, 24, 36, 18, 36, 54, 3, 6, 9, 6, 12, 18, 9, 18, 27, 6, 12, 18, 12, 24, 36, 18, 36, 54, 9, 18, 27, 18, 36, 54, 27, 54, 81}, ...

MATHEMATICA

a[1] = {1, 2, 3}; a[2] = {1, 2, 3, 2, 4, 6, 3, 6, 9}; a[n_] := a[n] = Flatten[Table[a[n - 1][[m]]*a[n - 1], {m, 1, Length[a[n - 1]]}]]; w = Table[a[n], {n, 1, 3}]; Flatten[w]

CROSSREFS

Cf. A011764, A115245, A130831.

Sequence in context: A105933 A105315 A328912 * A131989 A305390 A344310

Adjacent sequences:  A130827 A130828 A130829 * A130831 A130832 A130833

KEYWORD

nonn,tabf

AUTHOR

Roger L. Bagula, Aug 20 2007

EXTENSIONS

Edited by N. J. A. Sloane, Jun 07 2008

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.

License Agreements, Terms of Use, Privacy Policy. .

Last modified December 3 22:32 EST 2021. Contains 349468 sequences. (Running on oeis4.)