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 1-3 of 3 results.

A307095 Let K_n = prefix of length n of Kolakoski sequence A000002; a(n) is the length of the longest palindromic suffix of K_n.

Original entry on oeis.org

1, 1, 2, 4, 2, 4, 3, 3, 2, 4, 6, 5, 7, 2, 4, 3, 5, 7, 9, 11, 13, 3, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 6, 3, 2, 4, 6, 5, 7, 2, 4, 3, 3, 2, 4, 6, 8, 10, 12, 6, 5, 7, 2, 4, 3, 5, 7, 9, 11, 13, 3, 2, 4, 6, 5, 7, 2, 4, 3, 5, 7, 6, 3, 2, 4, 6, 8, 10, 12, 2, 4
Offset: 1

Views

Author

Rémy Sigrist, Jun 04 2019

Keywords

Examples

			The first terms, alongside K_n with longest palindromic suffix in parentheses, are:
  n   a(n)  K_n
  --  ----  ------------------
   1     1  (1)
   2     1  1(2)
   3     2  1(22)
   4     4  (1221)
   5     2  122(11)
   6     4  12(2112)
   7     3  1221(121)
   8     3  12211(212)
   9     2  1221121(22)
  10     4  122112(1221)
  11     6  12211(212212)
  12     5  1221121(22122)
  13     7  122112(1221221)
  14     2  122112122122(11)
  15     4  12211212212(2112)
  16     3  1221121221221(121)
		

Crossrefs

See A220080 for a similar sequence.
Cf. A000002.

Programs

  • PARI
    See Links section.

Formula

a(n+1) <= a(n) + 2.

A308182 Let S_n = prefix of length n of Thue-Morse sequence A010060; let P = longest palindromic suffix of S_n; a(n) = length of P if P occurs just once as a factor of S_n, otherwise a(n) = 0.

Original entry on oeis.org

1, 1, 2, 4, 3, 3, 2, 4, 0, 0, 6, 8, 10, 12, 14, 16, 6, 8, 10, 12, 6, 8, 10, 12, 0, 0, 6, 8, 10, 12, 14, 16, 0, 0, 0, 0, 0, 0, 0, 0, 18, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44, 46, 48, 50, 52, 54, 56, 58, 60, 62, 64, 18, 20, 22, 24, 26, 28, 30, 32
Offset: 1

Views

Author

N. J. A. Sloane, Jun 04 2019

Keywords

Comments

The positions of the 0's are the lacunae.

Examples

			n: .. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 ...
T-M:  a b b a b a a b b  a  a  b  a  b  b  a ... (Thue-Morse)
a(n): 1 1 2 4 3 3 2 4 0  0  6  8 10 12 14 16 ...
Corresponding successive maximal palindromic suffixes P:
a (so a(1)=1), b, bb, abba (so a(4)=4), bab, aba, aa, baab, bb (but bb has already appeared, so a(9)=0), ...
		

Crossrefs

Programs

  • Perl
    See Links section.

Formula

a(n) equals A220080(n) or 0. - Rémy Sigrist, Jun 04 2019

Extensions

More terms from Rémy Sigrist, Jun 04 2019

A308659 a(1)=1; for n > 1, a(n) is the length of the longest palindromic suffix of (a(1), ..., a(n-1)).

Original entry on oeis.org

1, 1, 2, 1, 3, 1, 3, 3, 2, 1, 1, 2, 4, 1, 1, 2, 1, 3, 1, 3, 3, 2, 1, 1, 2, 4, 1, 1, 2, 1, 3, 1, 3, 3, 2, 1, 1, 2, 4, 1, 1, 2, 1, 3, 1, 3, 3, 2, 1, 1, 2, 4, 1, 1, 2, 1, 3, 1, 3, 3, 2, 1, 1, 2, 4, 1, 1, 2, 1, 3, 1, 3, 3, 2, 1, 1, 2, 4, 1, 1, 2, 1, 3, 1, 3, 3, 2
Offset: 1

Views

Author

Samuel B. Reid, Jun 15 2019

Keywords

Comments

The sequence repeats after 13 terms.

Examples

			   1
  [1], 1
  [1 , 1], 2
   1 , 1 ,[2], 1
   1 ,[1 , 2 , 1], 3
   1 , 1 , 2 , 1 ,[3], 1
   1 , 1 , 2 ,[1 , 3 , 1], 3
   1 , 1 , 2 , 1 ,[3 , 1 , 3], 3
   1 , 1 , 2 , 1 , 3 , 1 ,[3 , 3], 2
   1 , 1 , 2 , 1 , 3 , 1 , 3 , 3 ,[2], 1
   1 , 1 , 2 , 1 , 3 , 1 , 3 , 3 , 2 ,[1], 1
   1 , 1 , 2 , 1 , 3 , 1 , 3 , 3 , 2 ,[1 , 1], 2
   1 , 1 , 2 , 1 , 3 , 1 , 3 , 3 ,[2 , 1 , 1 , 2], 4
		

Crossrefs

Cf. A220080.

Formula

G.f.: (1 + x + 2*x^2 + x^3 + 3*x^4 + x^5 + 3*x^6 + 3*x^7 + 2*x^8 + x^9 + x^10 + 2*x^11 + 4*x^12)/(1 - x^13). - Stefano Spezia, Jul 21 2019
Showing 1-3 of 3 results.