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 1-10 of 10 results.

A077467 Sum of binary digits of A077465(n).

Original entry on oeis.org

1, 2, 2, 3, 3, 4, 5, 5, 6, 6, 7, 8, 8, 9, 9, 10, 10, 11, 12, 12, 13, 13, 14, 15, 15, 16, 16, 17, 18, 18, 19, 19, 20, 20, 21, 22, 22, 23, 23, 24, 25, 25, 26, 26, 27, 27, 28, 29, 29, 30, 30, 31, 32, 32, 33, 33, 34, 34, 35, 36, 36, 37, 37, 38, 39, 39, 40, 40, 41, 41, 42, 43, 43, 44
Offset: 1

Views

Author

Eric W. Weisstein, Nov 05 2002

Keywords

Crossrefs

A077466 a(n) = A006046(A077465(n)).

Original entry on oeis.org

1, 5, 11, 37, 103, 317, 967, 2869, 8639, 25853, 77623, 232997, 698735, 2096461, 6288871, 18867125, 56600351, 169802077, 509408279, 1528220741, 4584666319, 13753990765, 41261980487, 123785957845, 371357840767, 1114073555069
Offset: 1

Views

Author

Eric W. Weisstein, Nov 05 2002

Keywords

Crossrefs

A116520 a(0) = 0, a(1) = 1; a(n) = max { 4*a(k) + a(n-k) | 1 <= k <= n/2 }, for n > 1.

Original entry on oeis.org

0, 1, 5, 9, 25, 29, 45, 61, 125, 129, 145, 161, 225, 241, 305, 369, 625, 629, 645, 661, 725, 741, 805, 869, 1125, 1141, 1205, 1269, 1525, 1589, 1845, 2101, 3125, 3129, 3145, 3161, 3225, 3241, 3305, 3369, 3625, 3641, 3705, 3769, 4025, 4089, 4345, 4601, 5625
Offset: 0

Views

Author

Roger L. Bagula, Mar 15 2006

Keywords

Comments

Equivalently, a(n) = r*a(ceiling(n/2)) + s*a(floor(n/2)), a(0)=0, a(1)=1, for (r,s) = (1,4). - N. J. A. Sloane, Feb 16 2016
A 5-divide version of A084230.
Zero together with the partial sums of A102376. - Omar E. Pol, May 05 2010
Also, total number of cubic ON cells after n generations in a three-dimensional cellular automaton in which A102376(n-1) gives the number of cubic ON cells in the n-th level of the structure starting from the top. An ON cell remains ON forever. The structure looks like an irregular stepped pyramid, with n >= 1. - Omar E. Pol, Feb 13 2015
From Gary W. Adamson, Aug 27 2016: (Start)
The formula of Mar 26 2010 is equivalent to lim_{k->infinity} M^k of the following production matrix M:
1, 0, 0, 0, 0, 0, ...
5, 0, 0, 0, 0, 0, ...
4, 1, 0, 0, 0, 0, ...
0, 5, 0, 0, 0, 0, ...
0, 4, 1, 0, 0, 0, ...
0, 0, 5, 0, 0, 0, ...
0, 0, 4, 1, 0, 0, ...
0, 0, 0, 5, 0, 0, ...
...
The sequence with offset 1 divided by its aerated variant is (1, 5, 4, 0, 0, 0, ...). (End)

Crossrefs

Sequences of the form a(n) = r*a(ceiling(n/2)) + s*a(floor(n/2)), a(1)=1, for (r,s) = (1,1), (1,2), (2,1), (1,3), (2,2), (3,1), (1,4), (2,3), (3,2), (4,1): A000027, A006046, A064194, A130665, A073121, A268524, A116520, A268525, A268526, A268527.

Programs

  • Haskell
    import Data.List (transpose)
    a116520 n = a116520_list !! n
    a116520_list = 0 : zs where
       zs = 1 : (concat $ transpose
                          [zipWith (+) vs zs, zipWith (+) vs $ tail zs])
          where vs = map (* 4) zs
    -- Reinhard Zumkeller, Apr 18 2012
  • Maple
    a:=proc(n) if n=0 then 0 elif n=1 then 1 elif n mod 2 = 0 then 5*a(n/2) else 4*a((n-1)/2)+a((n+1)/2) fi end: seq(a(n),n=0..52);
  • Mathematica
    b[0] := 0 b[1] := 1 b[n_?EvenQ] := b[n] = 5*b[n/2] b[n_?OddQ] := b[n] = 4*b[(n - 1)/2] + b[(n + 1)/2] a = Table[b[n], {n, 1, 25}]

Formula

a(0) = 1, a(1) = 1; thereafter a(2n) = 5a(n) and a(2n+1) = 4a(n) + a(n+1).
Let r(x) = (1 + 5x + 4x^2). Then (1 + 5x + 9x^2 + 25x^3 + ...) = r(x) * r(x^2) * r(x^4) * r(x^8) * ... . - Gary W. Adamson, Mar 26 2010
a(n) = Sum_{k=0..n-1} 4^wt(k), where wt = A000120. - Mike Warburton, Mar 14 2019
a(n) = Sum_{k=0..floor(log_2(n))} 4^k*A360189(n-1,k). - Alois P. Heinz, Mar 06 2023

Extensions

Edited by N. J. A. Sloane, Apr 16 2006, Jul 02 2008

A084230 Cumulative minima of A006046(n)/n^theta, where theta=log(3)/log(2), is a local minimum.

Original entry on oeis.org

1, 3, 5, 11, 21, 43, 87, 171, 173, 347, 693, 1387, 2775, 5547, 5549, 11099, 22197, 44395, 88789, 177579, 355159, 710315, 710317, 1420635, 2841269, 5682539, 11365079, 22730155, 22730157, 45460315, 90920629, 181841259, 363682519
Offset: 1

Views

Author

Eric W. Weisstein, May 20 2003

Keywords

Comments

Includes terms missed by Horbarth's recurrence.

Crossrefs

A116522 a(0)=1, a(1)=1, a(n)=7*a(n/2) for n=2,4,6,..., a(n)=6*a((n-1)/2)+a((n+1)/2) for n=3,5,7,....

Original entry on oeis.org

0, 1, 7, 13, 49, 55, 91, 127, 343, 349, 385, 421, 637, 673, 889, 1105, 2401, 2407, 2443, 2479, 2695, 2731, 2947, 3163, 4459, 4495, 4711, 4927, 6223, 6439, 7735, 9031, 16807, 16813, 16849, 16885, 17101, 17137, 17353, 17569, 18865, 18901, 19117, 19333
Offset: 0

Views

Author

Roger L. Bagula, Mar 15 2006

Keywords

Comments

A 7-divide version of A084230.
The Harborth: f(2^k) = 3^k suggests that a family of sequences of the form: f(2^k) = prime(n)^k.
From Gary W. Adamson, Aug 27 2016: (Start)
Let M = the production matrix below. Then lim_{k->infinity} M^k generates the sequence with offset 1 by extracting the left-shifted vector.
1, 0, 0, 0, 0, ...
7, 0, 0, 0, 0, ...
6, 1, 0, 0, 0, ...
0, 7, 0, 0, 0, ...
0, 6, 1, 0, 0, ...
0, 0, 7, 0, 0, ...
0, 0, 6, 1, 0, ...
...
The sequence divided by its aerated variant is (1, 7, 6, 0, 0, 0, ...). (End)

Crossrefs

Programs

  • Maple
    a:=proc(n) if n=0 then 0 elif n=1 then 1 elif n mod 2 = 0 then 7*a(n/2) else 6*a((n-1)/2)+a((n+1)/2) fi end: seq(a(n),n=0..47);
    # second Maple program:
    b:= proc(n) option remember; `if`(n<0, 0,
          b(n-1)+x^add(i, i=Bits[Split](n)))
        end:
    a:= n-> subs(x=6, b(n-1)):
    seq(a(n), n=0..44);  # Alois P. Heinz, Mar 06 2023
  • Mathematica
    b[0] := 0; b[1] := 1; b[n_?EvenQ] := b[n] = 7*b[n/2]; b[n_?OddQ] := b[n] = 6*b[(n - 1)/2] + b[(n + 1)/2]; a = Table[b[n], {n, 1, 25}]

Formula

G.f.: (r(x) * r(x^2) * r(x^4) * r(x^8) * ...), where r(x) = (1 + 7x + 6x^2).
a(n) = Sum_{k=0..n-1} 6^wt(k), where wt = A000120. - Mike Warburton, Mar 14 2019
a(n) = Sum_{k=0..floor(log_2(n))} 6^k*A360189(n-1,k). - Alois P. Heinz, Mar 06 2023

Extensions

Edited by N. J. A. Sloane, Apr 16 2005

A116525 a(0)=1, a(1)=1, a(n) = 11*a(n/2) for even n, and a(n) = 10*a((n-1)/2) + a((n+1)/2) for odd n >= 3.

Original entry on oeis.org

0, 1, 11, 21, 121, 131, 231, 331, 1331, 1341, 1441, 1541, 2541, 2641, 3641, 4641, 14641, 14651, 14751, 14851, 15851, 15951, 16951, 17951, 27951, 28051, 29051, 30051, 40051, 41051, 51051, 61051, 161051, 161061, 161161, 161261, 162261, 162361, 163361, 164361
Offset: 0

Views

Author

Roger L. Bagula, Mar 15 2006

Keywords

Comments

From Gary W. Adamson, Aug 30 2016: (Start)
Let M =
1, 0, 0, 0, 0, ...
11, 0, 0, 0, 0, ...
10, 1, 0, 0, 0, ...
0, 11, 0, 0, 0, ...
0, 10, 1, 0, 0, ...
0, 0, 11, 0, 0, ...
0, 0, 10, 1, 0, ...
...
Then lim_{k->infinity} M^k converges to a single nonzero column giving the sequence.
The sequence divided by its aerated variant is (1, 11, 10, 0, 0, 0, ...). (End)

Crossrefs

Programs

  • Maple
    a:=proc(n) if n=0 then 0 elif n=1 then 1 elif n mod 2 = 0 then 11*a(n/2) else 10*a((n-1)/2)+a((n+1)/2) fi end: seq(a(n),n=0..42);
  • Mathematica
    b[0] := 0; b[1] := 1; b[n_?EvenQ] := b[n] = 11*b[n/2]; b[n_?OddQ] := b[n] = 10*b[(n - 1)/2] + b[(n + 1)/2]; a = Table[b[n], {n, 1, 25}]

Formula

Let r(x) = (1 + 11x + 10x^2). The sequence is r(x) * r(x^2) * r(x^4) * r(x^8) * ... - Gary W. Adamson, Aug 30 2016
a(n) = Sum_{k=0..n-1} 10^wt(k), where wt = A000120. - Mike Warburton, Mar 14 2019
a(n) = Sum_{k=0..floor(log_2(n))} 10^k*A360189(n-1,k). - Alois P. Heinz, Mar 06 2023

Extensions

Edited by N. J. A. Sloane, Apr 16 2005

A116526 a(0)=1, a(1)=1, a(n) = 9*a(n/2) for even n >= 2, and a(n) = 8*a((n-1)/2) + a((n+1)/2) for odd n >= 3.

Original entry on oeis.org

0, 1, 9, 17, 81, 89, 153, 217, 729, 737, 801, 865, 1377, 1441, 1953, 2465, 6561, 6569, 6633, 6697, 7209, 7273, 7785, 8297, 12393, 12457, 12969, 13481, 17577, 18089, 22185, 26281, 59049, 59057, 59121, 59185, 59697, 59761, 60273, 60785, 64881, 64945, 65457, 65969
Offset: 0

Views

Author

Roger L. Bagula, Mar 15 2006

Keywords

Comments

A 9-divide version of A084230.
The interest this one has is in the prime form of even odd 2^n+1, 2^n.
From Gary W. Adamson, Aug 30 2016: (Start)
Let M =
1, 0, 0, 0, 0, ...
9, 0, 0, 0, 0, ...
8, 1, 0, 0, 0, ...
0, 9, 0, 0, 0, ...
0, 8, 1, 0, 0, ...
0, 0, 9, 0, 0, ...
0, 0, 8, 1, 0, ...
...
Then M^k converges to a single nonzero column giving the sequence.
The sequence divided by its aerated variant is (1, 9, 8, 0, 0, 0, ...). (End)

Crossrefs

Programs

  • Maple
    a:=proc(n) if n=0 then 0 elif n=1 then 1 elif n mod 2 = 0 then 9*a(n/2) else 8*a((n-1)/2)+a((n+1)/2) fi end: seq(a(n),n=0..45);
  • Mathematica
    b[0] := 0; b[1] := 1; b[n_?EvenQ] := b[n] = 9*b[n/2]; b[n_?OddQ] := b[n] = 8*b[(n - 1)/2] + b[(n + 1)/2]; a = Table[b[n], {n, 1, 25}]

Formula

a(n) = Sum_{k=0..n-1} 8^wt(k), where wt = A000120. - Mike Warburton, Mar 14 2019
a(n) = Sum_{k=0..floor(log_2(n))} 8^k*A360189(n-1,k). - Alois P. Heinz, Mar 06 2023

Extensions

Edited by N. J. A. Sloane, Apr 16 2006

A077464 Stolarsky-Harborth constant; lim inf_{n->oo} F(n)/n^theta, where F(n) is the number of odd binomial coefficients in the first n rows and theta=log(3)/log(2).

Original entry on oeis.org

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

Views

Author

Eric W. Weisstein, Nov 06 2002

Keywords

Comments

The limit supremum of F(n)/n^theta is 1. - Charles R Greathouse IV, Oct 30 2016
Named by Finch (2003) after Kenneth B. Stolarsky and Heiko Harborth. Stolarsky (1977) evaluated that its value is in the interval [0.72, 0.815], and Harborth (1977) calculated the value 0.812556. - Amiram Eldar, Dec 03 2020

Examples

			0.812556559016006387694882...
		

References

  • Steven R. Finch, Mathematical Constants, Cambridge University Press, 2003, pp. 145-151.

Crossrefs

Formula

Equals lim inf_{n->oo} A006046(n)/n^A020857. - Amiram Eldar, Dec 03 2020

A116524 a(0)=1, a(1)=1, a(n) = 13*a(n/2) for n=2,4,6,..., a(n) = 12*a((n-1)/2) + a((n+1)/2) for n=3,5,7,....

Original entry on oeis.org

0, 1, 13, 25, 169, 181, 325, 469, 2197, 2209, 2353, 2497, 4225, 4369, 6097, 7825, 28561, 28573, 28717, 28861, 30589, 30733, 32461, 34189, 54925, 55069, 56797, 58525, 79261, 80989, 101725, 122461, 371293, 371305, 371449, 371593, 373321
Offset: 0

Views

Author

Roger L. Bagula, Mar 15 2006

Keywords

Comments

A 13-divide version of A084230.
The Harborth : f(2^k)=3^k suggests that a family of sequences of the form: f(2^k)=Prime[n]^k There does indeed seem to be an infinite family of such functions.

Crossrefs

Programs

  • Maple
    a:=proc(n) if n=0 then 0 elif n=1 then 1 elif n mod 2 = 0 then 13*a(n/2) else 12*a((n-1)/2)+a((n+1)/2) fi end: seq(a(n),n=0..40);
  • Mathematica
    b[0] := 0; b[1] := 1; b[n_?EvenQ] := b[n] = 13*b[n/2]; b[n_?OddQ] := b[n] = 12*b[(n - 1)/2] + b[(n + 1)/2]; a = Table[b[n], {n, 1, 25}]

Formula

a(n) = Sum_{k=0..n-1} 12^wt(k), where wt = A000120. - Mike Warburton, Mar 14 2019

Extensions

Edited by N. J. A. Sloane, Apr 16 2005

A116523 a(0)=1, a(1)=1, a(n) = 17*a(n/2) for n=2,4,6,..., a(n) = 16*a((n-1)/2) + a((n+1)/2) for n=3,5,7,....

Original entry on oeis.org

0, 1, 17, 33, 289, 305, 561, 817, 4913, 4929, 5185, 5441, 9537, 9793, 13889, 17985, 83521, 83537, 83793, 84049, 88145, 88401, 92497, 96593, 162129, 162385, 166481, 170577, 236113, 240209, 305745, 371281, 1419857, 1419873, 1420129, 1420385
Offset: 0

Views

Author

Roger L. Bagula, Mar 15 2006

Keywords

Comments

A 17-divide version of A084230.
The Harborth : f(2^k)=3^k suggests that a family of sequences of the form: f(2^k)=Prime[n]^k There does indeed seem to be an infinite family of such functions.

Crossrefs

Programs

  • Maple
    a:=proc(n) if n=0 then 0 elif n=1 then 1 elif n mod 2 = 0 then 17*a(n/2) else 16*a((n-1)/2)+a((n+1)/2) fi end: seq(a(n),n=0..38);
  • Mathematica
    b[0] := 0; b[1] := 1; b[n_?EvenQ] := b[n] = 17*b[n/2]; b[n_?OddQ] := b[n] = 16*b[(n - 1)/2] + b[(n + 1)/2]; a = Table[b[n], {n, 1, 25}]

Formula

a(n) = Sum_{k=0..n-1} 16^wt(k), where wt = A000120. - Mike Warburton, Mar 22 2019

Extensions

Edited by N. J. A. Sloane, Apr 16 2005
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