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.

Previous Showing 11-15 of 15 results.

A091841 Records in A091840.

Original entry on oeis.org

1, 3, 9, 32, 119, 463, 1837, 7332, 29307, 117203, 468785
Offset: 0

Views

Author

N. J. A. Sloane, Mar 10 2004

Keywords

Comments

Each term is roughly 4 times the previous term.

Crossrefs

Extensions

a(8)-a(10) from John P. Linderman, May 30 2004

A091842 Lengths of suffix blocks associated with A091799.

Original entry on oeis.org

1, 1, 1, 3, 1, 1, 1, 3, 1, 1, 1, 3, 1, 1, 1, 10, 1, 1, 1, 3, 1, 1, 1, 3, 1, 1, 1, 3, 1, 1, 1, 10, 1, 1, 1, 3, 1, 1, 1, 3, 1, 1, 1, 3, 1, 1, 1, 10, 1, 1, 1, 3, 1, 1, 1, 3, 1, 1, 1, 3, 1, 1, 1, 42, 1, 1, 1, 3, 1, 1, 1, 3, 1, 1, 1, 3, 1, 1, 1, 10, 1, 1, 1, 3, 1, 1, 1, 3, 1, 1, 1, 3, 1, 1, 1, 10
Offset: 1

Views

Author

N. J. A. Sloane, Mar 10 2004

Keywords

Comments

The suffix blocks are what is called "glue string" in the paper by Gijswijt et al. (2007). Roughly speaking, these are the terms appended before the sequence goes on with a copy of all its initial terms up to the current position. (In the present sequence, when this happens, then this initial segment will actually be repeated for a total of 4 copies. Therefore each suffix block will start with a "4".) - M. F. Hasler, Aug 08 2018

Examples

			The first suffix block or "glue string" of length 10 is "4454444455", occurring as A091799(5760309077..5760309086). This is also the first occurrence of "55" in A091799. The first suffix block of length 42 is "4454444455"."444445"^5."55" (where . is concatenation) which occurs approximately at position 4.56*10^38. This is also the first occurrence of "555" in A091799. - _M. F. Hasler_, Aug 08 2018, corrected Sep 30 2018
		

Crossrefs

Programs

  • PARI
    print_A091842(LIM=oo,A=[],c=#A)={while(#Ak||break; k=m); A=concat(A,max(k,4)); if(k<4,#A>1&&print1(#A-c",");c=#A))} \\ M. F. Hasler, Aug 09 2018

Formula

a(n) = A091843(valuation(n-1,4)) for n < 259. For larger n, the index n must be increased by the number of terms "200" which occur* up to n-1 (* e.g., at n = 256, 511, 766, 1277, 1532, ...). - M. F. Hasler, Aug 09 2018

A091843 Records in A091842.

Original entry on oeis.org

1, 3, 10, 42, 200, 983, 4892, 24434, 122141
Offset: 0

Views

Author

N. J. A. Sloane, Mar 10 2004

Keywords

Crossrefs

Extensions

a(6)-a(8) from John P. Linderman, May 30 2004

A357067 Decimal expansion of the limit of A091411(k)/2^(k-1) as k goes to infinity.

Original entry on oeis.org

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

Views

Author

Levi van de Pol, Oct 22 2022

Keywords

Comments

In the article "The first occurrence of a number in Gijswijt's sequence", this constant is called epsilon_1. Its existence is proved in Theorem 7.2. The constant occurs in a direct formula (Theorem 7.11) for A091409(n), the first occurrence of the integer n in Gijswijt's sequence A090822.

Examples

			3.48669886438365597023...
		

Crossrefs

Programs

  • Python
    import math
    from mpmath import *
    # warning: 0.1 and mpf(1/10) are incorrect. Use mpf(1)/mpf(10)
    mp.dps=60
    def Cn(X):
        l=len(X)
        cn=1
        for i in range(1, int(l/2)+1):
            j=i
            while(X[l-j-1]==X[l-j-1+i]):
                j=j+1
                if j>=l:
                    break
            candidate=int(j/i)
            if candidate>cn:
                cn=candidate
        return cn
    def epsilon():
        A=[2] # level-2 Gijswijt sequence
        number=1 # number of S strings encountered
        position=0 # position of end of last S
        value=mpf(1) # approximation for epsilon1
        for i in range(1,6000):
            k=Cn(A)
            A.append(max(2,k))
            if k<2:
                value=value+mpf(i-position)/mpf(2**number)
                position=mpf(i)
                number+=1
        return value
    print("epsilon_1: ",epsilon())

Formula

Equal to 1 + Sum_{k>=1} A091579(k)/2^k. Proved in Corollary 7.3 of the article "The first occurrence of a number in Gijswijt's sequence".

A091845 Records in sequence of lengths of suffix blocks associated with A091844.

Original entry on oeis.org

1, 3, 11, 55, 315, 1872, 11205, 67195
Offset: 0

Views

Author

N. J. A. Sloane, Mar 10 2004

Keywords

Crossrefs

Extensions

a(5)-a(7) from John P. Linderman, May 30 2004.
Previous Showing 11-15 of 15 results.