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 31-37 of 37 results.

A111429 Tribonacci(hexanacci(n)).

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 0, 1, 2, 24, 3136, 53798080, 8607945812375585, 220376367601372354229355484029120, 78531983922879942351416192215114163135375656803468317366190276600
Offset: 0

Views

Author

Jonathan Vos Post, Nov 13 2005

Keywords

Crossrefs

Programs

  • Maple
    a:= n-> (<<0|1|0>, <0|0|1>, <1|1|1>>^((<<0|1|0|0|0|0>, <0|0|1|0|0|0>,
        <0|0|0|1|0|0>, <0|0|0|0|1|0>, <0|0|0|0|0|1>, <1|1|1|1|1|1>>^n)[1, 6]))[1, 3]:
    seq(a(n), n=0..14);  # Alois P. Heinz, Nov 07 2018

Formula

a(n) = A000073(A001592(n)).

A143662 a(n) is the number of n-tosses having a run of 6 or more heads for a fair coin (i.e., probability is a(n)/2^n).

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 1, 3, 8, 20, 48, 112, 256, 575, 1275, 2798, 6088, 13152, 28240, 60320, 128257, 271623, 573216, 1205880, 2529680, 5293264, 11050496, 23021311, 47868151, 99357390, 205897508, 426042552, 880346272, 1816750912, 3744698241, 7709963787, 15857441096, 32582726508, 66886894112
Offset: 0

Views

Author

DoZerg (daidodo(AT)gmail.com), Aug 28 2008

Keywords

Comments

a(n-1) is the number of compositions of n with at least one part >=7. - Joerg Arndt, Aug 06 2012

Programs

  • Mathematica
    LinearRecurrence[{3,-1,-1,-1,-1,-1,-2},{0,0,0,0,0,0,1},40] (* Harvey P. Dale, Dec 06 2018 *)
  • PARI
    N=66;  x='x+O('x^N);
    gf = (1-x)/(1-2*x); /* A011782(n): compositions of n */
    gf -= 1/(1 - (x+x^2+x^3+x^4+x^5+x^6)); /* A001592(n+5): compositions of n into parts <=6 */
    v143662=Vec(gf + 'a0);  v143662[1]=0; /* kludge to get all terms */
    v143662 /* show terms */
    /* Joerg Arndt, Aug 06 2012 */

Formula

G.f.: x^6/ ( (2*x-1)*(x^6+x^5+x^4+x^3+x^2+x-1) ). - Joerg Arndt, Aug 06 2012
a(n) = 2^n - A001592(n+6). - R. J. Mathar, Aug 06 2012

A181190 Maximal length of chain-addition sequence mod 10 with window of size n.

Original entry on oeis.org

1, 60, 124, 1560, 4686, 1456, 18744, 585936, 4882810, 212784
Offset: 1

Views

Author

Alexander Dashevsky (atanvarnoalda(AT)gmail.com), Oct 10 2010

Keywords

Comments

Chain addition mod 10 with window n: take an n-digit 'seed'. Take the sum of its digits mod 10 and append to the seed. Repeat with the last n digits of the string, until the seed appears again.
This sequence shows the lengths of the longest sequences for different window sizes.
a(1)-a(10) all occur for seed 1 (among others). If this is always true, the sequence continues: 406224, 12695306, 4272460934, 380859180, 122070312496, 518798826, 3433227539058. - Lars Blomberg, Feb 12 2013
Comment from Michel Lagneau, Jan 20 2017, edited by N. J. A. Sloane, Jan 24 2017: (Start)
If seed 1 is always as good as or better than any other, as seems likely, then this sequence has the following alternative description.
Consider the n initial terms of an infinite sequence S(k, n) of decimal digits given by 0, 0,..., 0, 1. The succeeding terms are given by the final digits in the sum of the n immediately preceding terms. The sequence lists the period of each sequence corresponding to n = 2, 3, ...
a(2) = period of A000045 mod 10 (Fibonacci numbers mod 10) = A001175(10).
a(3) = period of A000073 mod 10 (tribonacci numbers mod 10) = A046738(10).
a(4) = period of A000078 mod 10 (tetranacci numbers mod 10) = A106295(10).
a(5) = period of A001591 mod 10 (pentanacci numbers mod 10) = A106303(10).
a(6) = period of A001592 mod 10 (hexanacci numbers mod 10).
a(7) = period of A122189 mod 10 (heptanacci numbers mod 10).
a(8) = period of A079262 mod 10 (octanacci numbers mod 10).
a(4) = 1560 because the four initial terms 0, 0, 0, 1 => S(k, 4) = 0, 0, 0, 1, 1, 2, 4, 8, 5, 9, 6, 8, 8, 1, 3, 0, 2, 6, 1, 9, 8, ... (tetranacci numbers mod 10). This sequence is periodic with period 1560:
S(1560 + 1, 4) = S(1, 4) = 0,
S(1560 + 2, 4) = S(2, 4) = 0,
S(1560 + 3, 4) = S(3, 4) = 0,
S(1560 + 4, 4) = S(4, 4) = 1.
(End)

Examples

			For n=2, the longest sequence begins with '01' (among others):
01123583145943707741561785381909987527965167303369549325729101.
It is 60 digits long (not counting the second '01' at the end).
For n=3, one of the longest sequences begins again with '001':
00112473441944756893025746770415061742394699425184352079627546556679289964992013
48570291225960516297849144970639807524172091001 (124 digits long without the second '001').
		

Crossrefs

Extensions

a(8)-a(10) from Lars Blomberg, Feb 12 2013

A349903 Array read by ascending antidiagonals. Inverse Euler transform of the right-shifted k-bonacci numbers.

Original entry on oeis.org

0, 0, 1, 0, 1, 0, 0, 1, 1, -1, 0, 0, 1, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 1, 2, -1, 0, 0, 0, 0, 1, 2, 2, 0, 0, 0, 0, 0, 0, 1, 3, 4, 0, 0, 0, 0, 0, 0, 1, 2, 6, 5, 0, 0, 0, 0, 0, 0, 0, 1, 4, 10, 8, 0, 0, 0, 0, 0, 0, 0, 1, 2, 7, 18, 11, 0, 0, 0, 0, 0, 0, 0, 0, 1, 4, 14, 31, 18, 0, 0
Offset: 0

Views

Author

Peter Luschny, Dec 05 2021

Keywords

Examples

			Array starts:
[0] 0, 1, 0, -1, 0,  0, 0,  0,  0,  0,  0,  0,   0, ...
[1] 0, 1, 1,  0, 0, -1, 0,  0,  0,  0,  0,  0,   0, ...
[2] 0, 1, 1,  1, 2,  2, 4,  5,  8, 11, 18, 25,  40, ...
[3] 0, 0, 1,  1, 2,  3, 6, 10, 18, 31, 56, 96, 172, ...
[4] 0, 0, 0,  1, 1,  2, 4,  7, 14, 26, 50, 93, 178, ...
[5] 0, 0, 0,  0, 1,  1, 2,  4,  8, 15, 30, 58, 114, ...
[6] 0, 0, 0,  0, 0,  1, 1,  2,  4,  8, 16, 31,  62, ...
[7] 0, 0, 0,  0, 0,  0, 1,  1,  2,  4,  8, 16,  32, ...
[8] 0, 0, 0,  0, 0,  0, 0,  1,  1,  2,  4,  8,  16, ...
[9] 0, 0, 0,  0, 0,  0, 0,  0,  1,  1,  2,  4,   8, ...
.
Compare the rows with the columns of A349802.
		

Crossrefs

Rows are the inverse Euler transforms of A063524, A057427, A000045, A000073, A000078, A001591, A001592.

Programs

  • Maple
    read transforms;
    F := proc(n, k) option remember;
         ifelse(k < 2, k, add(F(n, k-j), j = 1..min(n, k))) end:
    Frow := (n, len) -> [seq(0, j = 0..n-3), seq(F(n, k), k = 0..len)]:
    Arow := (n, len) -> EULERi(Frow(n, len)):
    for n from 0 to 9 do Arow(n, 14 - n) od;

A111435 a(n) = Fibonacci(hexanacci(n)).

Original entry on oeis.org

0, 0, 0, 0, 0, 1, 1, 1, 3, 21, 987, 2178309, 6557470319842, 59425114757512643212875125, 3016128079338728432528443992613633888712980904400501
Offset: 0

Views

Author

Jonathan Vos Post, Nov 13 2005

Keywords

Examples

			a(0) = Fibonacci(hexanacci(0)) = A000045(A001592(0)) = A000045(0) = 0.
a(1) = Fibonacci(hexanacci(1)) = A000045(A001592(1)) = A000045(0) = 0.
a(2) = Fibonacci(hexanacci(2)) = A000045(A001592(2)) = A000045(0) = 0.
a(3) = Fibonacci(hexanacci(3)) = A000045(A001592(3)) = A000045(0) = 0.
a(4) = Fibonacci(hexanacci(4)) = A000045(A001592(4)) = A000045(0) = 0.
a(5) = Fibonacci(hexanacci(5)) = A000045(A001592(5)) = A000045(1) = 1.
a(6) = Fibonacci(hexanacci(6)) = A000045(A001592(6)) = A000045(1) = 1.
a(7) = Fibonacci(hexanacci(7)) = A000045(A001592(7)) = A000045(2) = 1.
a(8) = A000045(A001592(8)) = A000045(4) = 3.
a(9) = A000045(A001592(9)) = A000045(8) = 21.
a(10) = A000045(A001592(10)) = A000045(16) = 987.
a(11) = A000045(A001592(11)) = A000045(32) = 2178309.
a(12) = A000045(A001592(12)) = A000045(63) = 6557470319842.
		

Crossrefs

Programs

  • Maple
    b:= proc(n) option remember; `if`(n<5, 0,
          `if`(n=5, 1, add(b(n-j), j=1..6)))
        end:
    a:= n-> (<<0|1>, <1|1>>^b(n))[1,2]:
    seq(a(n), n=0..14);  # Alois P. Heinz, Aug 09 2018

Formula

a(n) = A000045(A001592(n)).

A111438 Fibonacci(heptanacci(n)), restricted to nonzero heptanacci numbers.

Original entry on oeis.org

1, 1, 1, 3, 21, 987, 2178309, 10610209857723, 155576970220531065681649693, 33449372971981195681356806732944396691005381570580873
Offset: 0

Views

Author

Jonathan Vos Post, Nov 14 2005

Keywords

Examples

			a(0) = Fibonacci(heptanacci(0)) = A000045(A066178(0)) = A000045(1) = 1.
a(1) = Fibonacci(heptanacci(1)) = A000045(A066178(1)) = A000045(1) = 1.
a(2) = Fibonacci(heptanacci(2)) = A000045(A066178(2)) = A000045(2) = 1.
a(3) = Fibonacci(heptanacci(3)) = A000045(A066178(3)) = A000045(4) = 3.
a(4) = Fibonacci(heptanacci(4)) = A000045(A066178(4)) = A000045(8) = 21.
a(5) = Fibonacci(heptanacci(5)) = A000045(A066178(5)) = A000045(16) = 987.
a(6) = A000045(A066178(6)) = A000045(32) = 2178309.
a(7) = A000045(A066178(7)) = A000045(64) = 10610209857723.
a(8) = A000045(A066178(8)) = A000045(127) = 155576970220531065681649693.
		

Crossrefs

Formula

a(n) = A000045(A066178(n)).

Extensions

Corrected by T. D. Noe, Nov 16 2006

A158921 Positions of hexanacci numbers in the EKG sequence.

Original entry on oeis.org

1, 2, 3, 8, 17, 31, 51, 112, 234, 464, 931, 1855, 3687, 4877
Offset: 1

Views

Author

Parthasarathy Nambi, Mar 30 2009

Keywords

Examples

			The hexanacci number 7617 is located at position 4877 in the EKG sequence.
		

Crossrefs

Previous Showing 31-37 of 37 results.