cp's OEIS Frontend

A131383(n) = sum of n-th row;

A000027(n) = T(n,1);

A000120(n) = T(n,2) for n>1;

A053735(n) = T(n,3) for n>2;

A053737(n) = T(n,4) for n>3;

A053824(n) = T(n,5) for n>4;

A053827(n) = T(n,6) for n>5;

A053828(n) = T(n,7) for n>6;

A053829(n) = T(n,8) for n>7;

A053830(n) = T(n,9) for n>8;

A007953(n) = T(n,10) for n>9;

A053831(n) = T(n,11) for n>10;

A053832(n) = T(n,12) for n>11;

A053833(n) = T(n,13) for n>12;

A053834(n) = T(n,14) for n>13;

A053835(n) = T(n,15) for n>14;

A053836(n) = T(n,16) for n>15;

A007395(n) = T(n,n-1) for n>1;

A000012(n) = T(n,n).

a(n) = Sum_{i=0..m} d(i)*9^i, where Sum_{i=0..m} d(i)*3^i is the base-3 representation of n.

Numbers that can be written using only digits 0, 1 and 2 in base 9. Also, write n in base 3, read as base 9: (3) [n] (9) in base change notation. a(3n+k) = 9a(n)+k for k in {0,1,2}. - Franklin T. Adams-Watters, Jul 24 2006

Also, every term k corresponds to a unique pair i,j with k = a(i) + 3*a(j) (similarly to the Moser-de Bruijn sequence). - Luis Rato, May 02 2024

Also the fixed point of the morphism 0->{0,1,2,3,4,5,6,7,8,9,10}, 1->{1,2,3,4,5,6,7,8,9,10,11}, 2->{2,3,4,5,6,7,8,9,10,11,12}, etc. - Robert G. Wilson v, Jul 27 2006

Also: a(n) = A053824(5^k+n-1) in the limit k->infinity, where k plays the role of a row index in A053824. (See the comment by M. F. Hasler for the proof.)

This means: if A053824 is regarded as a triangle then the rows converge to this sequence.

See conjecture in the entry A000120, and the case of base 2 in A063787.

From R. J. Mathar, Dec 09 2010: (Start)

In base b=5, A053824 starts counting up from 1 each time the index wraps around a power of b: A053824(b^k)=1.

Obvious recurrences are A053824(m*b^k+i) = m+A053824(i), 1 <= m < b-1, 0 <= i < b^(k-1).

So A053824 can be decomposed into a triangle T(k,n) = A053824(b^k+n-1), assuming that column indices start at n=1; row lengths are (b-1)*b^k.

There is a self-similarity in these sequences; a sawtooth structure of periodicity b is added algebraically on top of a sawtooth structure of periodicity b^2, on top of a periodicity b^3 etc. This leads to some "fake" finitely periodic substructures in the early parts of each row of T(.,.): often, but not always, a(n+b)=1+a(n). Often, but not always, a(n+b^2)=1+a(n) etc.

The common part of the rows T(.,.) grows with the power of b as shown in the recurrence above, and defines a(n) in the limit of large row indices k. (End)

The two definitions agree because the first 5^r terms in each row correspond to numbers 5^r, 5^r+1,...,5^r+(5^r-1), which are written in base 5 as a leading 1 plus the digits of 0,...,5^r-1. - M. F. Hasler, Dec 09 2010

From Omar E. Pol, Dec 10 2010: (Start)

In the scatter plots of these sequences, the basic structure is an element with b^2 points, where b is the associated base. (Scatter plots are created with the "graph" button of a sequence.) Sketches of these structures look as follows, the horizontal axis a squeezed version of the index n, b consecutive points packed vertically, and the vertical axis a(n):

........................................................

................................................ * .....

............................................... ** .....

..................................... * ...... *** .....

.................................... ** ..... **** .....

.......................... * ...... *** .... ***** .....

......................... ** ..... **** ... ****** .....

............... * ...... *** .... ***** ... ***** ......

.............. ** ..... **** .... **** .... **** .......

.... * ...... *** ..... *** ..... *** ..... *** ........

... ** ...... ** ...... ** ...... ** ...... ** .........

... * ....... * ....... * ....... * ....... * ..........

........................................................

... b=2 ..... b=3 ..... b=4 ..... b=5 ..... b=6 ........

. A000120 . A053735 . A053737 . A053824 . A053827 ......

. A063787 . A173523 . A173524 . A173525 . A173526 ......

........................................................

............................................. * ........

............................................ ** ........

........................... * ............. *** ........

.......................... ** ............ **** ........

........... *............ *** ........... ***** ........

.......... ** .......... **** .......... ****** ........

......... ***.......... ***** ......... ******* ........

........ **** ........ ****** ........ ******** ........

....... ***** ....... ******* ....... ********* ........

...... ****** ...... ******** ....... ******** .........

..... ******* ...... ******* ........ ******* ..........

..... ****** ....... ****** ......... ****** ...........

..... ***** ........ ***** .......... ***** ............

..... **** ......... **** ........... **** .............

..... *** .......... *** ............ *** ..............

..... ** ........... ** ............. ** ...............

..... * ............ * .............. * ................

........................................................

..... b=7 .......... b=8 ............ b=9 ..............

... A053828 ...... A053829 ........ A053830 ............

... A173527 ...... A173528 ........ A173529 ............(End)

Different from the highest power of 9 dividing n!, A090618.

T(n,k) is the least number of powers of n that add up to k. - Mohammed Yaseen, Nov 12 2022

If n has base-9 expansion abc..xyz with least significant digit z, a(n) = z - y + x - w + ...

The base 9/8 expansion is unique and thus the sum of digits function is well-defined.