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.

A004773 Numbers congruent to {0, 1, 2} mod 4: a(n) = floor(4*n/3).

Original entry on oeis.org

0, 1, 2, 4, 5, 6, 8, 9, 10, 12, 13, 14, 16, 17, 18, 20, 21, 22, 24, 25, 26, 28, 29, 30, 32, 33, 34, 36, 37, 38, 40, 41, 42, 44, 45, 46, 48, 49, 50, 52, 53, 54, 56, 57, 58, 60, 61, 62, 64, 65, 66, 68, 69, 70, 72, 73, 74, 76, 77, 78, 80, 81, 82, 84, 85, 86, 88, 89, 90
Offset: 0

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Author

Keywords

Comments

The sequence b(n) = floor((4/3)*(n+2)) appears as an upper bound in Fijavz and Wood.
Binary expansion does not end in 11.
From Guenther Schrack, May 04 2023: (Start)
The sequence is the interleaving of the sequences A008586, A016813, A016825, in that order.
Let S(n) = a(n) + a(n+1) + a(n+2). Then floor(S(n)/3) = A042968(n+1), round(S(n)/3) = a(n+1), ceiling(S(n)/3) = A042965(n+2). (End)

Crossrefs

Cf. A177702 (first differences), A000969 (partial sums).
Cf. A032766, this sequence, A001068, A047226, A047368, A004777.
Cf. similar sequences with formula n+i*floor(n/3) listed in A281899.

Programs

  • Magma
    [n: n in [0..100] | n mod 4 in [0..2]]; // Vincenzo Librandi, Dec 23 2010
    
  • Maple
    seq(floor(n/3)+n,n=0..68); # Gary Detlefs, Mar 20 2010
  • Mathematica
    f[n_] := Floor[4 n/3]; Array[f, 69, 0] (* Robert G. Wilson v, Dec 24 2010 *)
    fQ[n_] := Mod[n, 4] != 3; Select[ Range[0, 90], fQ] (* Robert G. Wilson v, Dec 24 2010 *)
    a[0] = 0; a[n_] := a[n] = a[n - 1] + 2 - If[ Mod[a[n - 1], 4] < 2, 1, 0]; Array[a, 69, 0] (* Robert G. Wilson v, Dec 24 2010 *)
    CoefficientList[ Series[x (1 + x + 2 x^2)/((1 - x) (1 - x^3)), {x, 0, 68}], x] (* Robert G. Wilson v, Dec 24 2010 *)
  • PARI
    a(n)=4*n\3 \\ Charles R Greathouse IV, Sep 27 2012

Formula

G.f.: x*(1+x+2*x^2)/((1-x)*(1-x^3)).
a(0) = 0, a(n+1) = a(n) + a(n) mod 4 + 0^(a(n) mod 4). - Reinhard Zumkeller, Mar 23 2003
a(n) = A004396(n) + A004523(n); complement of A004767. - Reinhard Zumkeller, Aug 29 2005
a(n) = floor(n/3) + n. - Gary Detlefs, Mar 20 2010
a(n) = (12*n-3+3*cos(2*n*Pi/3)+sqrt(3)*sin(2*n*Pi/3))/9. - Wesley Ivan Hurt, Sep 30 2017
E.g.f.: (3*exp(x)*(4*x - 1) + exp(-x/2)*(3*cos((sqrt(3)*x)/2) + sqrt(3)*sin((sqrt(3)*x)/2)))/9. - Stefano Spezia, Jun 09 2021
Sum_{n>=1} (-1)^(n+1)/a(n) = (sqrt(2)-1)*Pi/8 + sqrt(2)*log(sqrt(2)+2)/4 + (2-sqrt(2))*log(2)/8. - Amiram Eldar, Dec 05 2021
From Guenther Schrack, May 04 2023: (Start)
a(n) = (12*n - 3 + w^(2*n)*(w + 2) - w^n*(w - 1))/9 where w = (-1 + sqrt(-3))/2.
a(n) = 2*floor(n/3) + floor((n+1)/3) + floor((n+2)/3).
a(n) = (4*n - n mod 3)/3.
a(n) = a(n-3) + 4.
a(n) = a(n-1) + a(n-3) - a(n-4).
a(n) = 4*A002264(n) + A010872(n).
a(n) = A042968(n+1) - 1.
(End)

A047368 Numbers that are congruent to {0, 1, 2, 3, 4, 5} mod 7; a(n)=floor(7(n-1)/6).

Original entry on oeis.org

0, 1, 2, 3, 4, 5, 7, 8, 9, 10, 11, 12, 14, 15, 16, 17, 18, 19, 21, 22, 23, 24, 25, 26, 28, 29, 30, 31, 32, 33, 35, 36, 37, 38, 39, 40, 42, 43, 44, 45, 46, 47, 49, 50, 51, 52, 53, 54, 56, 57, 58, 59, 60, 61, 63, 64, 65, 66, 67, 68, 70, 71, 72, 73, 74, 75, 77
Offset: 1

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Author

Keywords

Crossrefs

Programs

  • Magma
    [n : n in [0..100] | n mod 7 in [0..5]]; // Wesley Ivan Hurt, Jun 15 2016
  • Maple
    A047368:=n->(42*n-57-3*cos(Pi*n)-4*sqrt(3)*cos((4*n+1)*Pi/6)-12*sin((1-2*n)*Pi/6))/36: seq(A047368(n), n=1..100); # Wesley Ivan Hurt, Jun 15 2016
  • Mathematica
    Select[Range[0, 100], MemberQ[{0, 1, 2, 3, 4, 5}, Mod[#, 7]] &] (* Wesley Ivan Hurt, Jun 15 2016 *)
    LinearRecurrence[{1, 0, 0, 0, 0, 1, -1}, {0, 1, 2, 3, 4, 5, 7}, 100] (* Vincenzo Librandi, Jun 16 2016 *)
  • PARI
    a(n)=(n-1)*7\6 \\ M. F. Hasler, Oct 05 2014
    

Formula

G.f.: x^2*(1+x+x^2+x^3+x^4+2*x^5) / ( (1+x)*(1+x+x^2)*(x^2-x+1)*(x-1)^2 ). - R. J. Mathar, Dec 04 2011
From Wesley Ivan Hurt, Jun 15 2016: (Start)
a(n) = a(n-1) + a(n-6) - a(n-7) for n>7.
a(n) = (42*n-57-3*cos(Pi*n)-4*sqrt(3)*cos((4*n+1)*Pi/6)-12*sin((1-2*n)*Pi/6))/36.
a(6k) = 7k-2, a(6k-1) = 7k-3, a(6k-2) = 7k-4, a(6k-3) = 7k-5, a(6k-4) = 7k-6, a(6k-5) = 7k-7. (End)

Extensions

Crossrefs and explicit formula in name added by M. F. Hasler, Oct 05 2014

A248375 a(n) = floor(9*n/8).

Original entry on oeis.org

0, 1, 2, 3, 4, 5, 6, 7, 9, 10, 11, 12, 13, 14, 15, 16, 18, 19, 20, 21, 22, 23, 24, 25, 27, 28, 29, 30, 31, 32, 33, 34, 36, 37, 38, 39, 40, 41, 42, 43, 45, 46, 47, 48, 49, 50, 51, 52, 54, 55, 56, 57, 58, 59, 60, 61, 63, 64, 65, 66, 67, 68, 69, 70, 72, 73, 74, 75, 76, 77, 78, 79, 81, 82, 83, 84, 85, 86, 87, 88, 90, 91, 92, 93, 94, 95
Offset: 0

Views

Author

M. F. Hasler, Oct 05 2014

Keywords

Comments

Also: numbers not congruent to 8 (mod 9), or numbers whose base-9 expansion does not end in the digit "8".
Paz proves that for all n>0 there is a prime in Breusch's interval [n; a(n+3)], cf A248371.

Crossrefs

Programs

  • Magma
    [Floor(9*n/8): n in [0..90]]; // Bruno Berselli, Oct 06 2014
  • Mathematica
    Table[Floor[9 n/8], {n, 0, 90}] (* Bruno Berselli, Oct 06 2014 *)
  • PARI
    a(n)=9*n\8
    

Formula

G.f.: x*(1 + x + x^2 + x^3 + x^4 + x^5 + x^6 + 2*x^7) / ((1 + x)*(1 - x)^2*(1 + x^2)*(1 + x^4)). [Bruno Berselli, Oct 06 2014]
a(n) = n + floor(n/8) = a(n-1) + a(n-8) - a(n-9). [Bruno Berselli, Oct 06 2014]
a(n) = A168183(n+1) - 1. - Philippe Deléham, Dec 05 2013

A059537 Beatty sequence for zeta(3).

Original entry on oeis.org

1, 2, 3, 4, 6, 7, 8, 9, 10, 12, 13, 14, 15, 16, 18, 19, 20, 21, 22, 24, 25, 26, 27, 28, 30, 31, 32, 33, 34, 36, 37, 38, 39, 40, 42, 43, 44, 45, 46, 48, 49, 50, 51, 52, 54, 55, 56, 57, 58, 60, 61, 62, 63, 64, 66, 67, 68, 69, 70, 72, 73, 74, 75, 76, 78, 79, 80, 81, 82, 84, 85
Offset: 1

Views

Author

Mitch Harris, Jan 22 2001

Keywords

Crossrefs

Beatty complement is A059538.
Cf. A002117 (zeta(3)).

Programs

  • Mathematica
    Floor[Range[100]*Zeta[3]] (* Paolo Xausa, Jul 07 2024 *)
  • PARI
    { default(realprecision, 100); b=zeta(3); for (n = 1, 2000, write("b059537.txt", n, " ", floor(n*b)); ) } \\ Harry J. Smith, Jun 27 2009

Formula

a(n) = A047226(n+1), 1<=n<99. - R. J. Mathar, Oct 05 2008
a(n) = floor(n*zeta(3)). - Michel Marcus, Jan 04 2015

A047256 Numbers that are congruent to {0, 1, 2, 3, 5} mod 6.

Original entry on oeis.org

0, 1, 2, 3, 5, 6, 7, 8, 9, 11, 12, 13, 14, 15, 17, 18, 19, 20, 21, 23, 24, 25, 26, 27, 29, 30, 31, 32, 33, 35, 36, 37, 38, 39, 41, 42, 43, 44, 45, 47, 48, 49, 50, 51, 53, 54, 55, 56, 57, 59, 60, 61, 62, 63, 65, 66, 67, 68, 69, 71, 72, 73, 74, 75, 77, 78, 79
Offset: 1

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Author

Keywords

Crossrefs

Cf. A047226.

Programs

  • Mathematica
    Flatten[# + {0, 1, 2, 3, 5} & /@ (6 Range[0, 11])] (* or *)
    Select[Range[0, 67], MemberQ[{0, 1, 2, 3, 5}, Mod[#, 6]] &] (* Robert G. Wilson v, Sep 26 2016 *)
    LinearRecurrence[{1,0,0,0,1,-1},{0,1,2,3,5,6},60] (* Harvey P. Dale, Jul 20 2020 *)

Formula

G.f.: x^2*(1+x)*(x^3 + x^2 + 1) / ( (x^4 + x^3 + x^2 + x + 1)*(x-1)^2 ). - R. J. Mathar, Oct 08 2011
Sum_{n>=2} (-1)^n/a(n) = (3-2*sqrt(3))*Pi/36 + log(2+sqrt(3))/sqrt(3). - Amiram Eldar, Dec 17 2021
a(n) = n + floor(n/5) - 1. - Aaron J Grech, Oct 03 2024

A187343 Rank transform of the sequence floor(6n/5); complement of A187344.

Original entry on oeis.org

1, 3, 4, 6, 8, 10, 11, 13, 14, 17, 18, 20, 22, 23, 25, 27, 28, 30, 31, 34, 35, 37, 38, 40, 42, 44, 46, 47, 48, 51, 52, 54, 56, 57, 59, 61, 62, 64, 65, 68, 70, 71, 72, 74, 76, 78, 79, 81, 83, 85, 86, 88, 90, 91, 94, 95, 96, 98, 99, 102, 104, 105, 107, 108, 110, 112, 114, 115
Offset: 1

Views

Author

Clark Kimberling, Mar 08 2011

Keywords

Comments

See A187224.

Crossrefs

Programs

  • Mathematica
    seqA=Table[Floor[6n/5], {n, 1, 220}] (* A047226 *)
    seqB=Table[n, {n, 1, 220}];          (* A000027 *)
    jointRank[{seqA_, seqB_}]:={Flatten@Position[#1, {, 1}], Flatten@Position[#1, {, 2}]}&[Sort@Flatten[{{#1, 1}&/@seqA, {#1, 2}&/@seqB}, 1]];
    limseqU=FixedPoint[jointRank[{seqA, #1[[1]]}]&, jointRank[{seqA, seqB}]][[1]]                  (* A187343 *)
    Complement[Range[Length[seqA]], limseqU] (* A187344 *)
    (*by Peter J. C. Moses, Mar 07 2011*)

A303602 a(n) = Sum_{k = 0..n} k*binomial(2*n+1, k).

Original entry on oeis.org

0, 3, 25, 154, 837, 4246, 20618, 97140, 447661, 2028478, 9070110, 40122028, 175913250, 765561564, 3310623412, 14238676712, 60949133949, 259809601870, 1103420316566, 4670886541308, 19714134528598, 82985455688276, 348481959315660, 1460179866076504, 6106070639175122
Offset: 0

Views

Author

Bruno Berselli, May 09 2018

Keywords

Comments

Second bisection of A185251; the first bisection is A002699.
The terms are not congruent to 5 (mod 6).

Crossrefs

Programs

  • Maple
    seq(add(k*binomial(2*n+1,k),k=0..n),n=0..24); # Paolo P. Lava, May 10 2018
  • Mathematica
    Table[Sum[k Binomial[2 n + 1, k], {k, 0, n}], {n, 0, 30}]
    CoefficientList[Series[(1 + 4*x - Sqrt[1 - 4*x]) / (2*(1 - 4*x)^2), {x, 0, 25}], x] (* Vaclav Kotesovec, May 10 2018 *)
  • PARI
    a(n)=(2*n+1)*(4^n-binomial(2*n,n))/2 \\ Charles R Greathouse IV, Oct 23 2023
  • Sage
    [(2*n+1)*(4^n-binomial(2*n,n))/2 for n in (0..30)]
    

Formula

E.g.f.: ((1 + 8*x)*exp(2*x) - (1 + 4*x)*I_0(2*x) - 4*x*I_1(2*x))*exp(2*x)/2, where I_m(.) is the modified Bessel function of the first kind.
From Vaclav Kotesovec, May 10 2018: (Start)
G.f.: (1 + 4*x - sqrt(1 - 4*x)) / (2*(1 - 4*x)^2).
D-finite with recurrence: n*(2*n-1)*a(n) = 2*(2*n+1)*(4*n-3)*a(n-1) - 8*(2*n-1)*(2*n+1)*a(n-2). (End)
a(n) = (2*n + 1)*(4^n - binomial(2*n, n))/2.
a(n+1) - 4*a(n) = A164991(2*n+3).

A047421 Floor(8n/7).

Original entry on oeis.org

0, 1, 2, 3, 4, 5, 6, 8, 9, 10, 11, 12, 13, 14, 16, 17, 18, 19, 20, 21, 22, 24, 25, 26, 27, 28, 29, 30, 32, 33, 34, 35, 36, 37, 38, 40, 41, 42, 43, 44, 45, 46, 48, 49, 50, 51, 52, 53, 54, 56, 57, 58, 59, 60, 61, 62, 64, 65, 66, 67, 68, 69, 70, 72, 73, 74, 75
Offset: 0

Views

Author

Keywords

Comments

Up to the offset identical to A004777, cf formula. - M. F. Hasler, Oct 06 2014

Crossrefs

Programs

  • Mathematica
    Table[Floor[8 n/7], {n, 0, 80}] (* Bruno Berselli, Oct 06 2014 *)
    LinearRecurrence[{1,0,0,0,0,0,1,-1},{0,1,2,3,4,5,6,8},70] (* Harvey P. Dale, Mar 06 2016 *)
  • PARI
    a(n)=n\7+n \\ M. F. Hasler, Oct 06 2014

Formula

a(n) = A004777(n+1). - M. F. Hasler, Oct 06 2014
G.f.: x*(1 + x + x^2 + x^3 + x^4 + x^5 + 2*x^6) / (1 - x - x^7 + x^8). [Bruno Berselli, Oct 06 2014]
a(n) = n + floor(n/7) = a(n-1) + a(n-7) - a(n-8). [Bruno Berselli, Oct 06 2014]

Extensions

More terms from Ray Chandler, Sep 05 2004
Restored to version of early 2008 by M. F. Hasler, Oct 06 2014
Showing 1-8 of 8 results.