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 1-5 of 5 results.

A260708 a(2n) = n*(2*n+1), a(2n+7) = a(2n+1) + 12*n + 28, with a(1)=1, a(3)=6, a(5)=16.

Original entry on oeis.org

0, 1, 3, 6, 10, 16, 21, 29, 36, 46, 55, 68, 78, 93, 105, 122, 136, 156, 171, 193, 210, 234, 253, 280, 300, 329, 351, 382, 406, 440, 465, 501, 528, 566, 595, 636, 666, 709, 741, 786, 820, 868, 903, 953, 990, 1042, 1081, 1136, 1176, 1233, 1275, 1334, 1378
Offset: 0

Views

Author

Paul Curtz, Nov 17 2015

Keywords

Comments

Conjecture: this sequence is 0 followed by A264041.
After 3, if a(n) is prime then n == 1 (mod 6).
a(n) is a square for n = 0, 1, 5, 8, 145, 288, 1777, 6533, 9800, 168097, 332928, 2051425, 7539845, ...

Examples

			a(0) = 0*1 = 0,
a(1) = 1,
a(2) = 1*3 = 3,
a(3) = 6,
a(4) = 2*5 = 10,
a(5) = 16,
a(6) = 3*7 = 21,
a(7) = a(1) +12*0 +28 = 29, etc.

Links

Crossrefs

Cf. A000217, A008615, A014105, A260160, A260699, A264041.

Programs

  • Mathematica
    LinearRecurrence[{1, 1, -1, 0, 0, 1, -1, -1, 1}, {0, 1, 3, 6, 10, 16, 21, 29, 36}, 50] (* Bruno Berselli, Nov 18 2015 *)
  • PARI
    concat(0, Vec(-x*(x^6+x^5+3*x^4+2*x^3+2*x^2+2*x+1)/((x-1)^3*(x+1)^2*(x^2-x+1)*(x^2+x+1)) + O(x^100))) \\ Colin Barker, Nov 18 2015
  • Sage
    [n*(n+1)/2+(1-(-1)^n)*floor(n/6+1/3)/2 for n in (0..60)] # Bruno Berselli, Nov 18 2015

Formula

From Colin Barker, Nov 17 2015: (Start)
G.f.: x*(1 + 2*x + 2*x^2 + 2*x^3 + 3*x^4 + x^5 + x^6) / ((1 - x)^3*(1 + x)^2*(1 - x + x^2)*(1 + x + x^2)).
a(n) = a(n-1) + a(n-2) - a(n-3) + a(n-6) - a(n-7) - a(n-8) + a(n-9) for n>8. (End)
a(2*k) = A000217(2*k) by definition; for odd indices:
a(6*k+1) = 18*k^2 + 10*k + 1,
a(6*k+3) = 2*(9*k^2 + 11*k + 3),
a(6*k+5) = 2*(k + 1)*(9*k + 8), that is A178574.
a(n) = A260699(n) + A008615(n).
a(n) = n*(n + 1)/2 + (1 - (-1)^n)*floor(n/6 + 1/3)/2. [Bruno Berselli, Nov 18 2015]

Extensions

Edited by Bruno Berselli, Nov 18 2015

A077265 Number of cycles in the n-th order prism graph.

Original entry on oeis.org

14, 28, 52, 94, 170, 312, 584, 1114, 2158, 4228, 8348, 16566, 32978, 65776, 131344, 262450, 524630, 1048956, 2097572, 4194766, 8389114, 16777768, 33555032, 67109514, 134218430, 268436212, 536871724, 1073742694, 2147484578, 4294968288, 8589935648, 17179870306
Offset: 3

Views

Author

Eric W. Weisstein, Nov 01 2002

Keywords

Comments

Also the number of cycles in the n-th order web graph. - Eric W. Weisstein, Dec 17 2013
Also the number of minimal edge cuts in the n-dipyramidal graph. - Eric W. Weisstein, Oct 30 2024
A subsequence of A290699.

Links

Crossrefs

Cf. A077263, A260699.
Cf. A000079, A002378, A132109.

Programs

Formula

a(n) = 2^n+n*(n-1). - Eric W. Weisstein, Dec 16 2013
a(n) = 5*a(n-1)-9*a(n-2)+7*a(n-3)-2*a(n-4). - Colin Barker, May 06 2014
G.f.: -2*x^3*(6*x^3-19*x^2+21*x-7) / ((x-1)^3*(2*x-1)). - Colin Barker, May 06 2014
a(n) = A000079(n) + A002378(n-1). - Wesley Ivan Hurt, May 07 2014
a(n) = 2*A132109(n-1). - R. J. Mathar, May 23 2016

Extensions

More terms from Eric W. Weisstein, Dec 16 2013

A264938 a(n) = n*(2*n-1) + floor(n/3).

Original entry on oeis.org

0, 1, 6, 16, 29, 46, 68, 93, 122, 156, 193, 234, 280, 329, 382, 440, 501, 566, 636, 709, 786, 868, 953, 1042, 1136, 1233, 1334, 1440, 1549, 1662, 1780, 1901, 2026, 2156, 2289, 2426, 2568, 2713, 2862, 3016, 3173, 3334, 3500, 3669, 3842, 4020, 4201, 4386, 4576, 4769
Offset: 0

Views

Author

Paul Curtz, Nov 29 2015

Keywords

Comments

Sequence extended to the left:
..., 133, 102, 76, 53, 34, 20, 9, 2, 0, 1, 6, 16, 29, 46, 68, 93, ...
Conjecture: after 0, a(n) provides the first bisection of A264041.
Conjecture: 2, 9, 20, 34, 53, 76, 102, 133, ... is A248121.

Links

Crossrefs

Second bisection of A260708.
Cf. A000217, A002264, A016777, A016969, A017197, A017641, A099837, A248121, A256320, A260699, A264041.
Cf. A171452: A000217(n-1) + A002264(n).

Programs

  • Magma
    [n*(2*n-1)+Floor(n/3): n in [0..60]]; // Vincenzo Librandi, Dec 02 2015
  • Maple
    seq(n*(2*n-1) + floor(n/3), n=0..100); # Robert Israel, Dec 02 2015
  • Mathematica
    Table[n (2 n - 1) + Floor[n/3], {n, 0, 50}] (* Vincenzo Librandi, Dec 02 2015 *)
LinearRecurrence[{2,-1,1,-2,1},{0,1,6,16,29},60] (* Harvey P. Dale, Oct 13 2020 *)
  • PARI
    concat(0, Vec(x*(1+x)^2*(1+2*x)/((1-x)^3*(1+x+x^2)) + O(x^100))) \\ Colin Barker, Dec 02 2015
  • PARI
    a(n) = n*(2*n-1) + n\3; \\ Altug Alkan, Dec 01 2015

Formula

a(n) = a(n-3) + 12*n - 20 for n>2.
From Colin Barker, Dec 02 2015: (Start)
a(n) = 2*a(n-1) - a(n-2) + a(n-3) - 2*a(n-4) + a(n-5) for n>4.
G.f.: x*(1+x)^2*(1+2*x) / ((1-x)^3*(1+x+x^2)).
(End)
a(n) = A000217(2n-1) + A002264(n).
a(n) + a(-n) = 3*A256320(n).
a(n +8) - a(n -7) = 20*A016777(n).
a(n+16) - a(n-14) = 20*A016969(n).
a(n+23) - a(n-22) = 20*A017197(n).
a(n+31) - a(n-29) = 20*A017641(n).
Generalization of the previous four formulas:
a(n+30*k +8) - a(n-30*k -7) = 20*(4*k+1)*(3*n+1).
a(n+30*k+16) - a(n-30*k-14) = 20*(2*k+1)*(6*n+5).
a(n+30*k+24) - a(n-30*k-21) = 20*(4*k+3)*(3*n+4).
a(n+30*k+32) - a(n-30*k-28) = 20*(2*k+2)*(6*n+11).
E.g.f.: (6*x^2+4*x-1)*exp(x)/3 + (cos(sqrt(3)*x/2)/3 +sqrt(3)*sin(sqrt(3)*x/2)/9)*exp(-x/2). - Robert Israel, Dec 02 2015

Extensions

Edited by Bruno Berselli, Dec 01 2015

A260307 a(n) = a(n-1) + a(n-2) - a(n-3) + a(n-6) - a(n-7) - a(n-8) + a(n-9) with a(0) - a(8) as shown below.

Original entry on oeis.org

1, 2, 3, 4, 6, 5, 8, 7, 10, 9, 13, 10, 15, 12, 17, 14, 20, 15, 22, 17, 24, 19, 27, 20, 29, 22, 31, 24, 34, 25, 36, 27, 38, 29, 41, 30, 43, 32, 45, 34, 48, 35, 50, 37, 52, 39, 55, 40, 57, 42, 59, 44, 62, 45, 64, 47, 66, 49, 69, 50, 71, 52, 73, 54, 76, 55, 78
Offset: 0

Views

Author

Paul Curtz, Nov 22 2015

Keywords

Comments

A260708 difference table rows have the same nine-step recurrence:
0, 1, 3, 6, 10, 16, 21, 29, 36, 46, 55, 65, 78, 93, ...
1, 2, 3, 4, 6, 5, 8, 7, 10, 9, 13, 10, 15, 12, ... = a(n)
1, 1, 1, 2, -1, 3, -1, 3, -1, 4, -3, 5, -3, 5, ... = b(n)
0, 0, 1, -3, 4, -4, 4, -4, 5, -7, 8, -8, 8, -8, ... (see A042965(n)).
(b(2n) + b(2n+1) = A052901(n+2).)

Links

Crossrefs

Cf. A004767, A010718, A042965, A047212, A047282, A052901, A152467, A260160 (eight-step recurrence), A260699 (nine-step recurrence), A260708.

Programs

  • Magma
    I:=[1,2,3,4,6,5,8,7];[n le 8 select I[n] else Self(n-2) + Self(n-6) - Self(n-8): n in [1..70]]; // Vincenzo Librandi, Dec 26 2015
  • Mathematica
    RecurrenceTable[{a[n] == a[n-2] + a[n-6] - a[n-8], a[0]=1, a[1]=2, a[2]=3, a[3]=4, a[4]=6, a[5]=5, a[6]=8, a[7]=7}, a, {n,0,100}] (* G. C. Greubel, Nov 23 2015 *)
  • PARI
    Vec((x^6+x^5+3*x^4+2*x^3+2*x^2+2*x+1)/((x-1)^2*(x+1)^2*(x^2-x+1)*(x^2+x+1)) + O(x^100)) \\ Colin Barker, Nov 22 2015
  • PARI
    vector(100, n, n--; n + (-1)^n *((n+2)\6) + 1) \\ Altug Alkan, Nov 24 2015

Formula

a(2n) = A047282(n). a(2n+1) = A047212(n+1).
a(n) = A260708(n+1) - A260708(n).
a(n+6) = a(n) + period of length 2: repeat 7, 5.
a(2n) + a(2n+1) = 3 + 4*n.
a(n) = n + 1 + (-1)^n*A152467(n+2).
From Colin Barker, Nov 22 2015: (Start)
a(n) = a(n-2) + a(n-6) - a(n-8) for n>7.
G.f.: (x^6+x^5+3*x^4+2*x^3+2*x^2+2*x+1) / ((x-1)^2*(x+1)^2*(x^2-x+1)*(x^2+x+1)).
(End)

A265228 Interleave the even numbers with the numbers that are congruent to {1, 3, 7} mod 8.

Original entry on oeis.org

0, 1, 2, 3, 4, 7, 6, 9, 8, 11, 10, 15, 12, 17, 14, 19, 16, 23, 18, 25, 20, 27, 22, 31, 24, 33, 26, 35, 28, 39, 30, 41, 32, 43, 34, 47, 36, 49, 38, 51, 40, 55, 42, 57, 44, 59, 46, 63, 48, 65, 50, 67, 52, 71, 54, 73, 56, 75, 58, 79, 60, 81, 62, 83, 64, 87, 66
Offset: 0

Views

Author

Paul Curtz, Dec 06 2015

Keywords

Comments

b(n) denotes the sequence:
0, 0, 0, 0, 0, 0, 1, -1, 1, -1, 1, -1, 1, 2, -2, 2, -2, 2, -2, 2, 3, -3, 3, -3, 3, -3, 3, 4, -4, ..., and
c(n) = n + b(n) = n + floor((n+1)/7)*(-1)^((n+1) mod 7) provides:
0, 1, 2, 3, 4, 5, 7, 6, 9, 8, 11, 10, 13, 15, 12, 17, 14, 19, 16, 21, 23, 18, 25, 20, 27, 22, 29, ..., which is a permutation of A001477.
a(n) differs from c(n) because c(n) contains the terms of the form 8*k+5.

Links

Crossrefs

Cf. A001477, A004770, A005843, A047529, A079979, A260160, A260699, A260708.

Programs

  • Mathematica
    lim = 11; Riffle[Range[0, 6 lim, 2], Select[Range[8 lim], MemberQ[{1, 3, 7}, Mod[#, 8]] &]] (* Michael De Vlieger, Dec 06 2015 *)
  • PARI
    concat(0, Vec(x*(1+2*x+2*x^2+2*x^3+4*x^4+2*x^5+x^6)/((1-x)^2 *(1+x)^2*(1-x+x^2)*(1+x+x^2)) + O(x^100))) \\ Colin Barker, Dec 06 2015
  • PARI
    vector(100, n, n--; n+(1-(-1)^n)*floor(n/6+1/3)) \\ Altug Alkan, Dec 09 2015

Formula

a(n) = n + 2*A260160(n) = n + (1-(-1)^n)*floor(n/6+1/3). Therefore, for odd n, a(n) = A047529((n+1)/2); otherwise, a(n) = n.
a(n) = a(n-6) - (-1)^n + 7.
a(n) = A260708(n) - A260699(n-1) - A079979(n+3), with A260699(-1) = 0.
From Colin Barker, Dec 06 2015: (Start)
a(n) = a(n-2) + a(n-6) - a(n-8) for n > 7.
G.f.: x*(1+2*x+2*x^2+2*x^3+4*x^4+2*x^5+x^6) / ((1-x)^2*(1+x)^2*(1-x+x^2)*(1+x+x^2)). (End)
Showing 1-5 of 5 results.

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