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 1-8 of 8 results.

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

A093957 A091799(n) - 3.

Original entry on oeis.org

0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0
Offset: 1

Views

Author

N. J. A. Sloane, May 22 2004

Keywords

Comments

The purpose of A093955-A093958 is to compare A090822, A091787, A091799 and A091844 on the same "scale".
Sequence is unbounded.

Crossrefs

A091787 a(1) = 2. To get a(n+1), write the string a(1)a(2)...a(n) as xy^k for words x and y (where y has positive length) and k is maximized, i.e., k = the maximal number of repeating blocks at the end of the sequence so far. Then a(n+1) = max(k,2).

Original entry on oeis.org

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

Views

Author

N. J. A. Sloane, Mar 07 2004

Keywords

Comments

Here xy^k means the concatenation of the words x and k copies of y.
a(77709404388415370160829246932345692180) = 5 is the first time 5 appears.
This is also the concatenation of the glue strings of A090822, whose respective lengths are given in A091579. - M. F. Hasler, Oct 04 2018
This sequence is called the level-2 Gijswijt sequence.

Examples

			To get a(2): a(1) = 2 = (2)^1, so k = 1, a(2) = 2.
To get a(3): a(1)a(2) = 22 = (2)^2, so a(3) = k = 2.
To get a(4): a(1)a(2)a(3) = 222 = (2)^3, so a(3) = k = 3.
		

References

  • N. J. A. Sloane, Seven Staggering Sequences, in Homage to a Pied Puzzler, E. Pegg Jr., A. H. Schoen and T. Rodgers (editors), A. K. Peters, Wellesley, MA, 2009, pp. 93-110.

Crossrefs

Programs

  • PARI
    A091787(n, A=[])={while(#Ak||break; k=m); A=concat(A, k)); A} \\ M. F. Hasler, Oct 04 2018
    
  • Python
    from itertools import islice
    def c(w):
        for k in range(len(w), 0, -1):
            for l in range(1, len(w)//k + 1):
                if w[-k*l:] == w[-l:]*k: return k
    def agen(): # generator of terms
        alst, an = [], 2
        while True: yield an; alst.append(an); an = max(2, c(alst))
    print(list(islice(agen(), 99))) # Michael S. Branicky, Sep 10 2022

A091844 a(1) = 4. To get a(n+1), write the string a(1)a(2)...a(n) as xy^k for words x and y (where y has positive length) and k is maximized, i.e., k = the maximal number of repeating blocks at the end of the sequence so far. Then a(n+1) = max(k,4).

Original entry on oeis.org

4, 4, 4, 4, 4, 5, 4, 4, 4, 4, 4, 5, 4, 4, 4, 4, 4, 5, 4, 4, 4, 4, 4, 5, 4, 4, 4, 4, 4, 5, 5, 4, 4, 4, 4, 4, 5, 4, 4, 4, 4, 4, 5, 4, 4, 4, 4, 4, 5, 4, 4, 4, 4, 4, 5, 4, 4, 4, 4, 4, 5, 5, 4, 4, 4, 4, 4, 5, 4, 4, 4, 4, 4, 5, 4, 4, 4, 4, 4, 5, 4, 4, 4, 4, 4, 5, 4, 4, 4, 4, 4, 5, 5, 4, 4, 4, 4, 4, 5
Offset: 1

Views

Author

N. J. A. Sloane, Mar 10 2004

Keywords

Comments

Here xy^k means the concatenation of the words x and k copies of y.
The first '6' occurs at a(3908). - Sergio Pimentel, Jul 13 2015

Crossrefs

Programs

  • Mathematica
    maxBlockLength = 100; a[1] = 4; a[n_] := a[n] = Module[{rev = Reverse[Array[a, n - 1]]}, blockCount[blockLength_] := Module[{par, p1, k}, par = Partition[rev, blockLength]; If[par == {}, Return[1]]; p1 = First[par]; k = 1; While[k <= Length[par], If[par[[k]] != p1, Break[], k++]]; k - 1]; Max[Max[Array[blockCount, maxBlockLength]], 4]]; Array[a, 100] (* Michael De Vlieger, Jul 13 2015, after Jean-François Alcover at A091799 *)
  • PARI
    {A091844(Nmax, L=1, A=List(), f(A,m=3,L=0)=while( #A>=(m+1)*L++, while( A[#A-L*m+1..#A]==A[#A-L*(m+1)+1..#A-L], (m+++1)*L>#A&& break)); m,t) = while(#AA091799. - M. F. Hasler, Sep 30 2018

A093955 A090822(n) - 1.

Original entry on oeis.org

0, 0, 1, 0, 0, 1, 1, 1, 2, 0, 0, 1, 0, 0, 1, 1, 1, 2, 1, 0, 0, 1, 0, 0, 1, 1, 1, 2, 0, 0, 1, 0, 0, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 2, 2, 1, 0, 0, 1, 0, 0, 1, 1, 1, 2, 0, 0, 1, 0, 0, 1, 1, 1, 2, 1, 0, 0, 1, 0, 0, 1, 1, 1, 2, 0, 0, 1, 0, 0, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 2, 2, 1, 1, 1, 2, 1, 0
Offset: 1

Views

Author

N. J. A. Sloane, May 22 2004

Keywords

Comments

The purpose of A093955-A093958 is to compare A090822, A091787, A091799 and A091844 on the same "scale".
Sequence is unbounded. A 3 appears for the first time at n=220. A 4 appears for the first time at around n = 10^10^23.

Crossrefs

A093958 A091844(n) - 4.

Original entry on oeis.org

0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 1
Offset: 1

Views

Author

N. J. A. Sloane, May 22 2004

Keywords

Comments

The purpose of A093955-A093958 is to compare A090822, A091787, A091799 and A091844 on the same "scale".
Sequence is unbounded.

Crossrefs

A093149 a(1) = 4; a(n) = (n^(n+1)+2*n-3)/(n-1) for n > 1.

Original entry on oeis.org

4, 9, 42, 343, 3908, 55989, 960802, 19173963, 435848052, 11111111113, 313842837674, 9726655034463, 328114698808276, 11966776581370173, 469172025408063618, 19676527011956855059, 878942778254232811940, 41660902667961039785745, 2088331858752553232964202
Offset: 1

Views

Author

N. J. A. Sloane, May 21 2004

Keywords

Comments

This sequence represents the first step in which the Gijswijt's sequence (A090822), with a minimum value of n-1, reaches the value n+1 for the first time. For example, the first '3' in A090822 is in step 9, the first '4' in A091787 is in step 42, the first '5' in A091799 is in step 343 and so on. - Sergio Pimentel, Jul 15 2015

Crossrefs

Programs

  • Magma
    [4] cat [(n^(n+1)+2*n-3)/(n-1): n in [2..20]]; // Vincenzo Librandi, Jul 16 2015
  • Maple
    A093149:=n->(n^(n+1)+2*n-3)/(n-1): (4,seq(A093149(n), n=2..30)); # Wesley Ivan Hurt, Jul 15 2015
  • Mathematica
    {4}~Join~Table[(n^(n + 1) + 2 n - 3)/(n - 1), {n, 2, 19}] (* Michael De Vlieger, Jul 13 2015 *)
  • PARI
    main(size)=my(v=vector(size),i); v[1]=4; for(i=2,size, v[i]=(i^(i+1)+2*i-3)/(i-1)); v \\ Anders Hellström, Jul 13 2015
    

A093956 A091787(n) - 2.

Original entry on oeis.org

0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 1, 1, 1, 2, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 1, 1, 1, 2, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 1, 0, 0
Offset: 1

Views

Author

N. J. A. Sloane, May 22 2004

Keywords

Comments

The purpose of A093955-A093958 is to compare A090822, A091787, A091799 and A091844 on the same "scale".
Sequence is unbounded.

Crossrefs

Showing 1-8 of 8 results.