cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-2 of 2 results.

A093086 "Fibonacci in digits": start with a(0)=0, a(1)=1; repeatedly adjoin the digits of the sum of the next two terms.

Original entry on oeis.org

0, 1, 1, 2, 3, 5, 8, 1, 3, 9, 4, 1, 2, 1, 3, 5, 3, 3, 4, 8, 8, 6, 7, 1, 2, 1, 6, 1, 4, 1, 3, 8, 3, 3, 7, 7, 5, 5, 4, 1, 1, 1, 1, 6, 1, 0, 1, 4, 1, 2, 1, 0, 9, 5, 2, 2, 2, 7, 7, 1, 1, 5, 5, 3, 3, 1, 9, 1, 4, 7, 4, 4, 9, 1, 4, 8, 2, 6, 1, 0, 8, 6, 4, 1, 0, 1, 0, 5, 1, 1, 1, 1, 8, 1, 3, 1, 0, 5, 1, 2, 1, 0, 8, 7, 1, 8
Offset: 0

Views

Author

Bodo Zinser, Mar 20 2004

Keywords

Comments

Formally, define strings of digits S_i as follows. S_0={0}, S_1={0,1}. For n >= 1, let S_n={t_0, t_1, ..., t_z}. Then S_{n+1} is obtained by adjoining the digits of t_{n-1}+t_n to S_n. The sequence gives the limiting string S_oo.
All digits appear infinitely often, although the sequence is not periodic.

Examples

			After S_6 = {0,1,1,2,3,5,8} we have 5+8 = 13, so we get
S_7 = {0,1,1,2,3,5,8,1,3}. Then 8+1 = 9, so we get
S_8 = {0,1,1,2,3,5,8,1,3,9}. Then 1+3 = 4, so we get
S_9 = {0,1,1,2,3,5,8,1,3,9,4}, and so on.
		

Crossrefs

Programs

  • Maple
    with(linalg): A:=matrix(1,2,[0,1]): for n from 1 to 100 do if A[1,n]+A[1,n+1]<10 then A:=concat(A,matrix(1,1,A[1,n]+A[1,n+1])) else A:=concat(A,matrix(1,2,[1,A[1,n]+A[1,n+1]-10])) fi od: matrix(A); # Emeric Deutsch, May 31 2005
  • Mathematica
    Fold[Join[#, IntegerDigits[Total[#[[#2;; #2+1]]]]] &, {0, 1}, Range[100]] (* Paolo Xausa, Aug 18 2025 *)

Extensions

Edited by N. J. A. Sloane, Mar 20 2010

A339359 Irregular triangle read by rows; the first row simply contains the value 1; given the succession of digits of the n-th row, say [d_0, ..., d_k], the (n+1)-th row is [d_0, d_0+d_1, d_1+d_2, ..., d_{k-1}+d_k, d_k].

Original entry on oeis.org

1, 1, 1, 1, 2, 1, 1, 3, 3, 1, 1, 4, 6, 4, 1, 1, 5, 10, 10, 5, 1, 1, 6, 6, 1, 1, 1, 5, 6, 1, 1, 7, 12, 7, 2, 2, 6, 11, 7, 1, 1, 8, 8, 3, 9, 9, 4, 8, 7, 2, 8, 8, 1, 1, 9, 16, 11, 12, 18, 13, 12, 15, 9, 10, 16, 9, 1, 1, 10, 10, 7, 7, 2, 2, 3, 3, 9, 9, 4, 4, 3, 3, 6, 14, 10, 1, 1, 7, 15, 10, 1
Offset: 0

Views

Author

Rémy Sigrist, Dec 02 2020

Keywords

Comments

This sequence combines features of Pascal's triangle (A007318) and of A214365.
Rows 0 to 5 match that of Pascal's triangle, thereafter the values differ.
Every column is eventually periodic.

Examples

			The first rows are:
    1
    1, 1
    1, 2, 1
    1, 3, 3, 1
    1, 4, 6, 4, 1
    1, 5, 10, 10, 5, 1
    1, 6, 6, 1, 1, 1, 5, 6, 1
    1, 7, 12, 7, 2, 2, 6, 11, 7, 1
    1, 8, 8, 3, 9, 9, 4, 8, 7, 2, 8, 8, 1
    1, 9, 16, 11, 12, 18, 13, 12, 15, 9, 10, 16, 9, 1
		

Crossrefs

See A339379 for a similar sequence.

Programs

  • Mathematica
    NestList[Map[Total, Partition[Flatten[IntegerDigits[#]], 2, 1, {-1, 1}, 0]] &, {1}, 10] (* Paolo Xausa, Aug 19 2025 *)
  • PARI
    { r=[1]; for (n=0, 10, apply (v -> print1(v", "), r); d=concat(apply(digits, r)); r=vector(#d+1, k, if (k==1, d[1], k==#d+1, d[#d], d[k-1]+d[k]))) }
Showing 1-2 of 2 results.