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.

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A060494 a(n) = floor(n^4/64).

Original entry on oeis.org

0, 0, 0, 1, 4, 9, 20, 37, 64, 102, 156, 228, 324, 446, 600, 791, 1024, 1305, 1640, 2036, 2500, 3038, 3660, 4372, 5184, 6103, 7140, 8303, 9604, 11051, 12656, 14430, 16384, 18530, 20880, 23447, 26244, 29283, 32580, 36147, 40000, 44152, 48620, 53418, 58564, 64072
Offset: 0

Views

Author

Henry Bottomley, Mar 21 2001

Keywords

Examples

			a(9) = floor(9^4/64) = floor(6561/64) = floor(102.51562...) = 102.
		

Programs

  • Mathematica
    Floor[Range[0,50]^4/64] (* or *) LinearRecurrence[ {4,-6,4,-1,0,0,0,0,0,0,0,0,0,0,0,1,-4,6,-4,1},{0,0,0,1,4,9,20,37,64,102,156,228,324,446,600,791,1024,1305,1640,2036},50] (* Harvey P. Dale, May 30 2014 *)
  • PARI
    a(n) = { n^4\64 } \\ Harry J. Smith, Jul 06 2009

Formula

a(n) = floor(A000583(n)/64) = floor(A011863(n-1)/4). a(2n) = A059403(2n); a(2n-1) = A059403(2n-1) + A011861(n).
From R. J. Mathar, Mar 24 2011: (Start)
a(n) = 4*a(n-1) - 6*a(n-2) + 4*a(n-3) - a(n-4) + a(n-16) - 4*a(n-17) + 6*a(n-18) - 4*a(n-19) + a(n-20).
G.f.: -x^3 *(1 - x^2 + 4*x^3 - 4*x^4 - 3*x^6 + 4*x^7 - 3*x^8 + 4*x^9 - 4*x^10 + 4*x^11 - x^12 + x^14 + 4*x^5) / ( (1+x) *(x^2+1) *(x^4+1) *(x^8+1) *(x-1)^5 ). (End)

A081276 Floor(n^3/8).

Original entry on oeis.org

0, 0, 1, 3, 8, 15, 27, 42, 64, 91, 125, 166, 216, 274, 343, 421, 512, 614, 729, 857, 1000, 1157, 1331, 1520, 1728, 1953, 2197, 2460, 2744, 3048, 3375, 3723, 4096, 4492, 4913, 5359, 5832, 6331, 6859, 7414, 8000, 8615, 9261, 9938, 10648, 11390, 12167, 12977
Offset: 0

Views

Author

Paul Barry, Mar 15 2003

Keywords

Comments

a(2n) = n^3.

Crossrefs

Programs

  • Magma
    [Floor(n^3/8): n in [0..50]]; // Vincenzo Librandi, Aug 07 2013
  • Mathematica
    Floor[Range[0,50]^3/8] (* or *) LinearRecurrence[ {3,-3,1,0,0,0,0,1,-3,3,-1},{0,0,1,3,8,15,27,42,64,91,125},50] (* Harvey P. Dale, Jan 27 2012 *)

Formula

a(n) = floor(n^3/8).
G.f.: x^2*(-x^3-2*x^5+3*x^4+1+4*x^6+2*x^2-2*x^7+x^8)/((-1+x)^4*(1+x)*(1+x^2)*(x^4+1)). - R. J. Mathar, Jun 26 2009
a(0)=0, a(1)=0, a(2)=1, a(3)=3, a(4)=8, a(5)=15, a(6)=27, a(7)=42, a(8)=64, a(9)=91, a(10)=125, a(n)=3*a(n-1)-3*a(n-2)+a(n-3)+a(n-8)- 3*a(n-9)+ 3*a(n-10)-a (n-11). - Harvey P. Dale, Jan 27 2012

A175707 Number of ways to put n copies of 1,2,3,4 into sets.

Original entry on oeis.org

1, 15, 139, 862, 4079, 15791, 52450, 154279, 411180, 1009741, 2314278, 5000125, 10264997, 20152950, 38037517, 69323949, 122448455, 210271756, 351989816, 575711716, 921889652, 1447822620, 2233501928, 3389114724, 5064582169, 7461570579, 10848490675, 15579077786, 22115241763, 31054971635, 43166197978, 59427633555, 81077755892, 109673237289, 147158299390, 195946638641
Offset: 0

Views

Author

Keywords

Comments

Related to generalized Bell Numbers.
The n copies of each digit must be in different sets, and the sets must be nonempty.
Other definition: Number of ways to distribute n copies of 1,2,3,4 into an arbitrary number of (nonempty) sets. Due to the nature of sets, the same digit may not be several times in the same set.

Examples

			For n=1, the solution is the fourth term of Bell numbers A000110.
For n=2, one way to partition 2 copies of 1, 2 copies of 2, 2 copies of 3 and 2 copies of 4 is {1}{2}{34}{12}{34}. On the other hand {112}{34}{23}{4} is not allowed since the same numbers are in the same set {112}.
		

Crossrefs

Programs

  • Maple
    a:= n-> (5382*n^11 +236808*n^10 +4643760*n^9 +53507520*n^8 +402098796*n^7 +2067612624*n^6 +7421736960*n^5 +18616942080*n^4 +32101468047*n^3 +36555545268*n^2 +25131098880*n +8024016000 +7016625*(-1)^n*n^3 +84199500*(-1)^n*n^2 +359251200*(-1)^n*n +538876800*(-1)^n) /(2^11*3^7*5^2*7*11) +5/3^6*(-1)^n * (sin(n*Pi/3)/sqrt(3)+ cos(n*Pi/3));
    seq(a(n), n=0..40);
    seq(SeqBrnDJ(n,4)[5], n=1..6); # using the Maple package BABUSHKAS (see links)
  • Mathematica
    LinearRecurrence[{7, -17, 8, 36, -60, 4, 56, -22, -22, -22, 56, 4, -60, 36, 8, -17, 7, -1}, {1, 15, 139, 862, 4079, 15791, 52450, 154279, 411180, 1009741, 2314278, 5000125, 10264997, 20152950, 38037517, 69323949, 122448455, 210271756}, 36] (* Jean-François Alcover, Nov 13 2018 *)

Formula

a(n) = (5382*n^11 +236808*n^10 +4643760*n^9 +53507520*n^8 +402098796*n^7 +2067612624*n^6 +7421736960*n^5 +18616942080*n^4 +32101468047*n^3 +36555545268*n^2 +25131098880*n +8024016000 +7016625*(-1)^n*n^3 +84199500*(-1)^n*n^2 +359251200*(-1)^n*n +538876800*(-1)^n) / (2^11*3^7*5^2*7*11) +5/3^6*(-1)^n * (sin(n*Pi/3)/sqrt(3) +cos(n*Pi/3)).
Recurrence: a(n) -7*a(n-1) +17*a(n-2) -8*a(n-3) -36*a(n-4) +60*a(n-5) -4*a(n-6) -56*a(n-7) +22*a(n-8) +22*a(n-9) +22*a(n-10) -56*a(n-11) -4*a(n-12) +60*a(n-13) -36*a(n-14) -8*a(n-15) +17*a(n-16) -7*a(n-17) +a(n-18) = 0.
G.f.: (x^10 +8*x^9 +51*x^8 +136*x^7 +252*x^6 +300*x^5 +252*x^4 +136*x^3 +51*x^2 +8*x+1) / ((x^2+x+1)*(x+1)^4*(x-1)^12).

A061003 Nearest integer to n^5/25.

Original entry on oeis.org

0, 1, 10, 41, 125, 311, 672, 1311, 2362, 4000, 6442, 9953, 14852, 21513, 30375, 41943, 56794, 75583, 99044, 128000, 163364, 206145, 257454, 318505, 390625, 475255, 573956, 688415, 820446, 972000, 1145166, 1342177, 1565416, 1817417
Offset: 1

Views

Author

N. J. A. Sloane, May 15 2001

Keywords

Crossrefs

Programs

Formula

G.f.: x*(x^7+5x^6+x^5+10x^4+x^3+5x^2+x)/((1-x^5)*(1-x)^5).
Previous Showing 11-14 of 14 results.