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.

A178420 Partial sums of floor(2^n/3).

Original entry on oeis.org

0, 1, 3, 8, 18, 39, 81, 166, 336, 677, 1359, 2724, 5454, 10915, 21837, 43682, 87372, 174753, 349515, 699040, 1398090, 2796191, 5592393, 11184798, 22369608, 44739229, 89478471, 178956956, 357913926, 715827867, 1431655749, 2863311514
Offset: 1

Views

Author

Mircea Merca, Dec 21 2010

Keywords

Comments

Essentially the same as A011377: 0 followed by the terms of A011377. - Joerg Arndt, Apr 22 2016
Partial sums of A000975(n-1).

Examples

			a(5) = 0 + 1 + 2 + 5 + 10 = 18.
		

Crossrefs

Column k=2 of A368296.

Programs

  • Magma
    [Floor((4*2^n-3*n-4)/6): n in [1..30]]; // Vincenzo Librandi, Jun 23 2011
    
  • Maple
    seq(round((4*2^n-3*n-4)/6),n=1..50)
  • Mathematica
    f[n_] := Floor[(4 2^n - 3 n - 4)/6]; f[Range[60]] (* Vladimir Joseph Stephan Orlovsky, Jan 29 2011 *)
    CoefficientList[Series[x / ((1 + x) (1 - 2 x) (1 - x)^2), {x, 0, 50}], x] (* Vincenzo Librandi, Mar 26 2014 *)
    LinearRecurrence[{3,-1,-3,2},{0,1,3,8},40] (* or *) Accumulate[ Table[ Floor[ 2^n/3],{n,40}]] (* Harvey P. Dale, Dec 24 2015 *)
  • PARI
    a(n)=(4<Charles R Greathouse IV, Jul 31 2013

Formula

a(n) = A011377(n-1) for n >= 1. - Joerg Arndt, Apr 22 2016
a(n) = round((8*2^n - 6*n - 9)/12).
a(n) = floor((4*2^n - 3*n - 4)/6).
a(n) = ceiling((4*2^n - 3*n - 5)/6).
a(n) = round((4*2^n - 3*n - 4)/6).
a(n) = a(n-2) + 2^(n-1) - 1, n > 2.
From Bruno Berselli, Jan 15 2011: (Start)
a(n) = (8*2^n - 6*n - 9 + (-1)^n)/12.
G.f.: x^2/((1+x)*(1-2*x)*(1-x)^2). (End)
G.f.: Q(0)/(3*(1-x)^2), where Q(k) = 1 - 1/(4^k - 2*x*16^k/(2*x*4^k - 1/(1 + 1/(2*4^k - 8*x*16^k/(4*x*4^k + 1/Q(k+1)))))); (continued fraction). - Sergei N. Gladkovskii, May 21 2013
a(n) = 2*a(n-1) + floor(n/2) for n > 1. - Bruno Berselli, Apr 30 2014
a(n) = floor(2^(n+1)/3) - floor((n+1)/2). - Seiichi Manyama, Dec 22 2023

A368343 Square array T(n,k), n >= 3, k >= 0, read by antidiagonals downwards, where T(n,k) = Sum_{j=0..n} k^(n-j) * floor(j/3).

Original entry on oeis.org

1, 1, 1, 1, 2, 1, 1, 3, 3, 2, 1, 4, 7, 5, 2, 1, 5, 13, 16, 7, 2, 1, 6, 21, 41, 34, 9, 3, 1, 7, 31, 86, 125, 70, 12, 3, 1, 8, 43, 157, 346, 377, 143, 15, 3, 1, 9, 57, 260, 787, 1386, 1134, 289, 18, 4, 1, 10, 73, 401, 1562, 3937, 5547, 3405, 581, 22, 4
Offset: 3

Views

Author

Seiichi Manyama, Dec 22 2023

Keywords

Examples

			Square array begins:
  1,  1,   1,    1,    1,     1,     1, ...
  1,  2,   3,    4,    5,     6,     7, ...
  1,  3,   7,   13,   21,    31,    43, ...
  2,  5,  16,   41,   86,   157,   260, ...
  2,  7,  34,  125,  346,   787,  1562, ...
  2,  9,  70,  377, 1386,  3937,  9374, ...
  3, 12, 143, 1134, 5547, 19688, 56247, ...
		

Crossrefs

Columns k=0..4 give A002264, A130518, A178455, A368344, A368345.

Programs

  • PARI
    T(n, k) = sum(j=0, n, k^(n-j)*(j\3));

Formula

T(n,k) = T(n-3,k) + Sum_{j=0..n-3} k^j.
T(n,k) = 1/(k-1) * Sum_{j=0..n} floor(k^j/(k^2+k+1)) = Sum_{j=0..n} floor(k^j/(k^3-1)) for k > 1.
T(n,k) = (k+1)*T(n-1,k) - k*T(n-2,k) + T(n-3,k) - (k+1)*T(n-4,k) + k*T(n-5,k).
G.f. of column k: x^3/((1-x) * (1-k*x) * (1-x^3)).
T(n,k) = 1/(k-1) * (floor(k^(n+1)/(k^3-1)) - floor((n+1)/3)) for k > 1.

A097137 Convolution of 3^n and floor(n/2).

Original entry on oeis.org

0, 0, 1, 4, 14, 44, 135, 408, 1228, 3688, 11069, 33212, 99642, 298932, 896803, 2690416, 8071256, 24213776, 72641337, 217924020, 653772070, 1961316220, 5883948671, 17651846024, 52955538084, 158866614264, 476599842805
Offset: 0

Views

Author

Paul Barry, Jul 29 2004

Keywords

Comments

a(n+1) gives partial sums of A033113 and second partial sums of A015518(n+1). Binomial transform of {0,0,1,1,4,4,16,16,...}.
Partial sums of floor(3^n/8) = round(3^n/8). - Mircea Merca, Dec 28 2010

Crossrefs

Column k=3 of A368296.
Cf. A033113.

Programs

  • GAP
    a:=[0,0,1,4];; for n in [5..30] do a[n]:=4*a[n-1]-2*a[n-2]-4*a[n-3] +3*a[n-4]; od; a; # G. C. Greubel, Jul 14 2019
  • Magma
    [Round((3*3^n-4*n-4)/16): n in [0..30]]; // Vincenzo Librandi, Jun 25 2011
    
  • Maple
    A097137 := proc(n) add( floor(3^i/8),i=0..n) ; end proc:
  • Mathematica
    CoefficientList[Series[x^2/((1-x)^2(1-3x)(1+x)),{x,0,30}],x]  (* Harvey P. Dale, Mar 11 2011 *)
  • PARI
    my(x='x+O('x^30)); concat([0,0], Vec(x^2/((1-x)^2*(1-3*x)*(1+x)))) \\ G. C. Greubel, Jul 14 2019
    
  • Sage
    (x^2/((1-x)^2*(1-3*x)*(1+x))).series(x, 30).coefficients(x, sparse=False) # G. C. Greubel, Jul 14 2019
    

Formula

G.f.: x^2/((1-x)^2*(1-3*x)*(1+x)).
a(n) = 4*a(n-1) - 2*a(n-2) - 4*a(n-3) + 3*a(n-4).
a(n) = Sum_{k=0..n} floor((n-k)/2)*3^k = Sum_{k=0..n} floor(k/2)*3^(n-k).
From Mircea Merca, Dec 26 2010: (Start)
a(n) = round((3*3^n - 4*n - 4)/16) = floor((3*3^n - 4*n - 3)/16) = ceiling((3*3^n - 4*n - 5)/16) = round((3*3^n - 4*n - 3)/16).
a(n) = a(n-2) + (3^(n-1)-1)/2, n > 2. (End)
a(n) = (floor(3^(n+1)/8) - floor((n+1)/2))/2. - Seiichi Manyama, Dec 22 2023

A097138 Convolution of 4^n and floor(n/2).

Original entry on oeis.org

0, 0, 1, 5, 22, 90, 363, 1455, 5824, 23300, 93205, 372825, 1491306, 5965230, 23860927, 95443715, 381774868, 1527099480, 6108397929, 24433591725, 97734366910, 390937467650, 1563749870611, 6254999482455, 25019997929832
Offset: 0

Views

Author

Paul Barry, Jul 29 2004

Keywords

Comments

a(n+1) gives partial sums of A033114 and second partial sums of A015521.
Partial sums of 1/3*floor(4^n/5). - Mircea Merca, Dec 26 2010

Examples

			a(3) = 1/3*floor(4^0/5)+1/3*floor(4^1/5)+1/3*floor(4^2/5) +1/3*floor(4^3/5) = 0 + 0 + 1 + 4 = 5.
		

Crossrefs

Column k=4 of A368296.

Programs

  • Magma
    [(4^(n+2)-30*n+9*(-1)^n-25)/180: n in [0..30]]; // Vincenzo Librandi, May 31 2011
  • Maple
    A097138 := proc(n) (4^(n+2)-30*n+9*(-1)^n-25)/180 ; end proc: # R. J. Mathar, Jan 08 2011
  • Mathematica
    LinearRecurrence[{5,-3,-5,4},{0,0,1,5},30] (* Harvey P. Dale, Sep 17 2017 *)

Formula

G.f.: x^2/((1-x)*(1-4*x)*(1-x^2)).
a(n) = Sum_{k=0..n} floor((n-k)/2)4^k = Sum_{k=0..n} floor(k/2)*4^(n-k).
a(n) = 5*a(n-1) - 3*a(n-2) - 5*a(n-3) + 4*a(n-4).
From Mircea Merca, Dec 26 2010: (Start)
3*a(n) = round((16*4^n-30*n-25)/60) = floor((8*4^n-15*n-8)/30) = ceiling((8*4^n-15*n-17)/30) = round((8*4^n-15*n-8)/30).
a(n) = a(n-2)+(4^(n-1)-1)/3, n>1. (End)
a(n) = (4^(n+2)-30*n+9*(-1)^n-25)/180. - Bruno Berselli, Dec 27 2010
a(n) = (floor(4^(n+1)/15) - floor((n+1)/2))/3. - Seiichi Manyama, Dec 22 2023

A097139 Convolution of 5^n and floor(n/2).

Original entry on oeis.org

0, 0, 1, 6, 32, 162, 813, 4068, 20344, 101724, 508625, 2543130, 12715656, 63578286, 317891437, 1589457192, 7947285968, 39736429848, 198682149249, 993410746254, 4967053731280, 24835268656410, 124176343282061, 620881716410316
Offset: 0

Views

Author

Paul Barry, Jul 29 2004

Keywords

Comments

a(n+1) gives partial sums of A033115 and second partial sums of A015531.
Partial sums of (1/4)*floor(5^n/6) = (1/3)*floor(5^n/8). - Mircea Merca, Dec 27 2010

Crossrefs

Column k=5 of A368296.

Programs

  • Magma
    [5^(n+1)/96 -n/8 -3/32 +(-1)^n/24: n in [0..30]]; // Vincenzo Librandi, Jun 25 2011
  • Maple
    A097139 := proc(n) 5^(n+1)/96 -n/8 -3/32 +(-1)^n/24 ; end proc: # R. J. Mathar, Jan 08 2011
  • Mathematica
    f[n_] := Floor[5^n/6]/4; Accumulate@ Array[f, 24, 0]
    a[n_] := a[n] = 6 a[n - 1] - 4 a[n - 2] - 6 a[n - 3] + 5 a[n - 4]; a[0] = a[1] = 0; a[2] = 1; a[3] = 6; Array[a, 24, 0]
    CoefficientList[ Series[x^2/((1 - x) (1 - 5 x) (1 - x^2)), {x, 0, 23}], x] (* Robert G. Wilson v, Jan 02 2011 *)
    LinearRecurrence[{6,-4,-6,5},{0,0,1,6},30] (* Harvey P. Dale, Mar 16 2019 *)

Formula

a(n) = 5^(n+1)/96 -n/8 -3/32 +(-1)^n/24. - R. J. Mathar, Jan 08 2011
G.f.: x^2/((1-x)*(1-5*x)*(1-x^2)).
a(n) = 6*a(n-1) - 4*a(n-2) - 6*a(n-3) + 5*a(n-4).
a(n) = Sum_{k=0..n} floor((n-k)/2)*4^k = Sum_{k=0..n} floor(k/2)*4^(n-k).
From Mircea Merca, Dec 27 2010: (Start)
4*a(n) = round((5*5^n-12*n-9)/24) = floor((5*5^n-12*n-5)/24) = ceiling((5*5^n-12*n-13)/24) = round((5*5^n-12*n-5)/24).
a(n) = a(n-2) + (5^(n-1)-1)/4, n>1. (End)
a(n) = (floor(5^(n+1)/24) - floor((n+1)/2))/4. - Seiichi Manyama, Dec 22 2023

A178719 Partial sums of (1/5)*floor(6^n/7).

Original entry on oeis.org

0, 0, 1, 7, 44, 266, 1599, 9597, 57586, 345520, 2073125, 12438755, 74632536, 447795222, 2686771339, 16120628041, 96723768254, 580342609532, 3482055657201, 20892333943215, 125354003659300, 752124021955810, 4512744131734871, 27076464790409237, 162458788742455434, 974752732454732616
Offset: 0

Views

Author

Mircea Merca, Dec 26 2010

Keywords

Comments

Partial sums of A033116.

Examples

			a(3) = (1/5)*(floor(6^1/7) + floor(6^2/7) + floor(6^3/7)) = (1/5)*(0+5+30) = (1/5)*35 = 7.
		

Crossrefs

Column k=6 of A368296.
Cf. A033116.

Programs

  • Magma
    [(1/5)*Floor((12*6^n-35*n-12)/70): n in [0..30]]; // Vincenzo Librandi, Jun 21 2011
    
  • Maple
    A178719 := proc(n) add( floor(6^i/7)/5,i=0..n) ; end proc:
  • Mathematica
    f[n_] := Floor[6^n/7]/5; Accumulate@ Array[f, 22]
    CoefficientList[Series[x^2/((1+x)(1-6x)(1-x)^2), {x, 0, 50}], x] (* Vincenzo Librandi, Mar 26 2014 *)
  • PARI
    vector(30, n, n--; (((12*6^n-35*n-12)/70)\1)/5) \\ G. C. Greubel, Jan 24 2019
    
  • Sage
    [floor((12*6^n-35*n-12)/70)/5 for n in (0..30)] # G. C. Greubel, Jan 24 2019

Formula

a(n) = (1/5)*round((24*6^n - 70*n - 49)/140).
a(n) = (1/5)*floor((12*6^n - 35*n - 12)/70).
a(n) = (1/5)*ceiling((12*6^n - 35*n - 37)/70).
a(n) = (1/5)*round((12*6^n - 35*n - 12)/70).
a(n) = a(n-2) + (6^(n-1) - 1)/5, n > 1.
a(n) = 7*a(n-1) - 5*a(n-2) - 7*a(n-3) + 6*a(n-4), n > 3.
G.f.: x^2 / ( (1+x)*(1-6*x)*(1-x)^2 ).
a(n) = (24*6^n - 70*n + 25*(-1)^n - 49)/700. - Bruno Berselli, Feb 18 2011
a(n) = (floor(6^(n+1)/35) - floor((n+1)/2))/5. - Seiichi Manyama, Dec 22 2023

A178730 Partial sums of floor(7^n/8)/6.

Original entry on oeis.org

0, 1, 8, 58, 408, 2859, 20016, 140116, 980816, 6865717, 48060024, 336420174, 2354941224, 16484588575, 115392120032, 807744840232, 5654213881632, 39579497171433, 277056480200040, 1939395361400290, 13575767529802040, 95030372708614291, 665212608960300048, 4656488262722100348, 32595417839054702448
Offset: 1

Views

Author

Mircea Merca, Dec 26 2010

Keywords

Comments

Partial sums of A033117.

Examples

			a(3) = (1/6)*(floor(7/8) + floor(7^2/8) + floor(7^3/8)) = (1/6)*(0+6+42) = 8.
		

Crossrefs

Column k=7 of A368296.
Cf. A033117.

Programs

  • Magma
    [Floor((7*7^n-24*n-7)/48)/6: n in [1..30]]; // Vincenzo Librandi, Jun 21 2011
    
  • Maple
    A178730 := proc(n) add( floor(7^i/8)/6,i=0..n) ; end proc:
  • Mathematica
    CoefficientList[Series[x/((1+x)(1-7x)(1-x)^2), {x, 0, 50}], x] (* Vincenzo Librandi, Mar 26 2014 *)
  • PARI
    vector(30, n, (((7^(n+1)-24*n-7)/48)\1)/6) \\ G. C. Greubel, Jan 24 2019
    
  • Sage
    [floor((7^(n+1)-24*n-7)/48)/6 for n in (1..30)] # G. C. Greubel, Jan 24 2019

Formula

6*a(n) = round((7*7^n - 24*n - 16)/48).
6*a(n) = floor((7*7^n - 24*n - 7)/48).
6*a(n) = ceiling((7*7^n - 24*n - 25)/48).
6*a(n) = round((7*7^n - 24*n - 7)/48).
a(n) = a(n-2) + (7^(n-1) - 1)/6, n > 2.
a(n) = 8*a(n-1) - 6*a(n-2) - 8*a(n-3) + 7*a(n-4), n > 4.
G.f.: x^2/((1+x)*(1-7*x)*(1-x)^2).
a(n) = (7^(n+1) - 24*n + 9*(-1)^n - 16)/288. - Bruno Berselli, Jan 11 2011
a(n) = (floor(7^(n+1)/48) - floor((n+1)/2))/6. - Seiichi Manyama, Dec 22 2023

A178827 Partial sums of floor(8^n/9)/7.

Original entry on oeis.org

0, 1, 9, 74, 594, 4755, 38043, 304348, 2434788, 19478309, 155826477, 1246611822, 9972894582, 79783156663, 638265253311, 5106122026496, 40848976211976, 326791809695817, 2614334477566545, 20914675820532370, 167317406564258970, 1338539252514071771, 10708314020112574179, 85666512160900593444, 685332097287204747564
Offset: 1

Views

Author

Mircea Merca, Dec 27 2010

Keywords

Examples

			a(3) = (1/7)*(floor(8/9) + floor(64/9) + floor(512/9)) = (1/7)*(0 + 7 + 56) = (1/7)*63 = 9.
		

Crossrefs

Column k=8 of A368296.
Cf. A033118.

Programs

  • GAP
    a:=[0,1,9,74];; for n in [5..30] do a[n]:=9*a[n-1]-7*a[n-2]-9*a[n-3] +8*a[n-4]; od; a; # G. C. Greubel, Jan 22 2019
  • Magma
    [ &+[Floor(8^k/9)/7: k in [1..n]]: n in [1..25] ]; // Bruno Berselli, Apr 28 2011
    (Decimal BASIC)
    FOR n=1 TO 1000
       PRINT n; (32*8^n-126*n-81+49*(-1)^n)/1764
    NEXT n
    END   ! Bruno Berselli, Apr 28 2011
    
  • Maple
    A178827 := proc(n) add( floor(8^i/9)/7,i=0..n) ; end proc:
  • Mathematica
    Rest[CoefficientList[Series[x^2/((1+x)*(1-8*x)*(1-x)^2), {x,0,30}],x]] (* G. C. Greubel, Jan 22 2019 *)
  • PARI
    my(x='x+O('x^30)); concat([0], Vec(x^2/((1+x)*(1-8*x)*(1-x)^2))) \\ G. C. Greubel, Jan 22 2019
    
  • Sage
    a=(x^2/((1+x)*(1-8*x)*(1-x)^2)).series(x, 30).coefficients(x, sparse=False); a[1:] # G. C. Greubel, Jan 22 2019
    

Formula

7*a(n) = round((32*8^n - 126*n - 81)/252).
7*a(n) = floor((16*8^n - 63*n - 16)/126).
7*a(n) = ceiling((16*8^n - 63*n - 65)/126).
7*a(n) = round((16*8^n - 63*n - 16)/126).
a(n) = a(n-2) + (8^(n-1) - 1)/7, n > 2.
a(n) = 9*a(n-1) - 7*a(n-2) - 9*a(n-3) + 8*a(n-4), n > 4.
G.f.: x^2/((1+x)*(1-8*x)*(1-x)^2).
7*a(n) = (32*8^n - 126*n - 81 + 49*(-1)^n)/252. - Bruno Berselli, Jan 19 2011
a(n) = (floor(8^(n+1)/63) - floor((n+1)/2))/7. - Seiichi Manyama, Dec 22 2023
Showing 1-8 of 8 results.