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 14 results. Next

A224790 a(n) = 3*9^n + 8.

Original entry on oeis.org

11, 35, 251, 2195, 19691, 177155, 1594331, 14348915, 129140171, 1162261475, 10460353211, 94143178835, 847288609451, 7625597484995, 68630377364891, 617673396283955, 5559060566555531, 50031545098999715, 450283905890997371, 4052555153018976275
Offset: 0

Views

Author

Eric M. Schmidt, Apr 18 2013

Keywords

Comments

Number of conjugacy classes in Ree group 2G2(3*9^n).

Crossrefs

Cf. A188161.

Programs

Formula

G.f.: 8/(1-x) + 3/(1-9*x).
a(n) = 10*a(n-1) - 9*a(n-2).
E.g.f.: 8*exp(x) + 3*exp(9*x). - G. C. Greubel, Nov 12 2019

A225928 a(n) = 4*16^n + 8*4^n + 17.

Original entry on oeis.org

29, 113, 1169, 16913, 264209, 4202513, 67141649, 1073872913, 17180393489, 274880004113, 4398054899729, 70368777732113, 1125900041060369, 18014399046352913, 288230378299195409, 4611686027017322513, 73786976329197944849, 1180591620854850256913
Offset: 0

Views

Author

Eric M. Schmidt, May 21 2013

Keywords

Comments

Number of conjugacy classes in Ree group 2F4(2*4^n).

Crossrefs

Programs

  • Mathematica
    LinearRecurrence[{21,-84,64},{29,113,1169},20] (* Harvey P. Dale, May 06 2016 *)
  • PARI
    a(n)=4*16^n+8*4^n+17 \\ Charles R Greathouse IV, May 22 2013
  • Sage
    [4*16^n + 8*4^n + 17 for n in [0..20]]
    

Formula

G.f.: 17/(1-x) + 8/(1-4x) + 4/(1-16x).
a(n) = 21*a(n-1) - 84*a(n-2) + 64*a(n-3) for n > 2. - Wesley Ivan Hurt, Oct 08 2017

A225938 Number of conjugacy classes in Chevalley group E_8(q) as q runs through the prime powers (A246655).

Original entry on oeis.org

1156, 12825, 97154, 519071, 6906102, 19543486, 49150839, 238045722, 889575240, 4600759094, 7439557452, 17980383618, 82034207430, 159213167411, 293713437009, 518754968088, 882274298862, 1136129443366, 3612770425152, 8189556710532, 11973138177210, 24340206797502
Offset: 1

Views

Author

Eric M. Schmidt, May 21 2013

Keywords

Crossrefs

Programs

  • Maple
    A225938 := proc(n)
        local q ;
        q := A246655(n) ;
        if modp(q,2) = 0 then
            q^8 + q^7 + 2*q^6 + 3*q^5 +  9*q^4 + 14*q^3 + 32*q^2 + 47*q +  70;
        elif modp(q,3) = 0 then
            q^8 + q^7 + 2*q^6 + 3*q^5 + 10*q^4 + 16*q^3 + 39*q^2 + 65*q + 102 ;
        elif modp(q,5) = 0 then
            q^8 + q^7 + 2*q^6 + 3*q^5 + 10*q^4 + 16*q^3 + 40*q^2 + 67*q + 111 ;
        else
            q^8 + q^7 + 2*q^6 + 3*q^5 + 10*q^4 + 16*q^3 + 40*q^2 + 67*q + 112 ;
        end if;
    end proc: # R. J. Mathar, Jan 09 2017
  • Mathematica
    qmax = 100;
    Reap[For[q = 2, q < qmax, q++, If[PrimePowerQ[q], cc = q^8 + q^7 + 2 q^6 + 3 q^5 + Which[Mod[q, 2] == 0, 9 q^4 + 14 q^3 + 32 q^2 + 47 q + 70, Mod[q, 3] == 0, 10 q^4 + 16 q^3 + 39 q^2 + 65 q + 102, Mod[q, 5] == 0, 10 q^4 + 16 q^3 + 40 q^2 + 67 q + 111, True, 10 q^4 + 16 q^3 + 40 q^2 + 67 q + 112]; Sow[cc]]]][[2, 1]] (* Jean-François Alcover, Mar 24 2020 *)
  • Sage
    def A225938(q) : return q^8 + q^7 + 2*q^6 + 3*q^5 + (9*q^4 + 14*q^3 + 32*q^2 + 47*q + 70 if q%2==0 else 10*q^4 + 16*q^3 + 39*q^2 + 65*q + 102 if q%3==0 else 10*q^4 + 16*q^3 + 40*q^2 + 67*q + 111 if q%5==0 else 10*q^4 + 16*q^3 + 40*q^2 + 67*q + 112)

Formula

Let q be the n-th prime power. Then a(n) is
q^8 + q^7 + 2q^6 + 3q^5 + 9q^4 + 14q^3 + 32q^2 + 47q + 70, q==0(mod 2);
q^8 + q^7 + 2q^6 + 3q^5 + 10q^4 + 16q^3 + 39q^2 + 65q + 102, q==0(mod 3);
q^8 + q^7 + 2q^6 + 3q^5 + 10q^4 + 16q^3 + 40q^2 + 67q + 111, q==0(mod 5);
q^8 + q^7 + 2q^6 + 3q^5 + 10q^4 + 16q^3 + 40q^2 + 67q + 112, otherwise.

A283070 Sierpinski tetrahedron or tetrix numbers: a(n) = 2*4^n + 2.

Original entry on oeis.org

4, 10, 34, 130, 514, 2050, 8194, 32770, 131074, 524290, 2097154, 8388610, 33554434, 134217730, 536870914, 2147483650, 8589934594, 34359738370, 137438953474, 549755813890, 2199023255554, 8796093022210, 35184372088834, 140737488355330, 562949953421314
Offset: 0

Views

Author

Peter M. Chema, Feb 28 2017

Keywords

Comments

Number of vertices required to make a Sierpinski tetrahedron or tetrix of side length 2^n. The sum of the vertices (balls) plus line segments (rods) of one tetrix equals the vertices of its larger, adjacent iteration. See formula.
Equivalently, the number of vertices in the (n+1)-Sierpinski tetrahedron graph. - Eric W. Weisstein, Aug 17 2017
Also the independence number of the (n+2)-Sierpinski tetrahedron graph. - Eric W. Weisstein, Aug 29 2021
Final digit alternates 4 and 0.

Crossrefs

Subsequence of A016957.
First bisection of A052548, A087288; second bisection of A049332, A133140, A135440.
Cf. A002023 (edge count).

Programs

Formula

G.f.: 2*(2 - 5*x)/((1 - x)*(1 - 4*x)).
a(n) = 5*a(n-1) - 4*a(n-2) for n > 1.
a(n+1) = a(n) + A002023(n).
a(n) = 2*A052539(n) = A188161(n) - 1 = A087289(n) + 1 = A056469(2*n+2) = A261723(4*n+1).
E.g.f.: 2*(exp(4*x) + exp(x)). - G. C. Greubel, Aug 17 2017

Extensions

Entry revised by Editors of OEIS, Mar 01 2017

A225929 Number of conjugacy classes in Chevalley group G_2(q) as q runs through the prime powers.

Original entry on oeis.org

16, 23, 32, 44, 72, 88, 107, 152, 204, 296, 332, 408, 584, 684, 791, 908, 1032, 1096, 1452, 1772, 1944, 2312, 2508, 2924, 3608, 3852, 4232, 4632, 5192, 5484, 6408, 6731, 7064, 8108, 9612, 10412, 10824, 11672, 12108, 13004, 14892, 15884, 16392, 16648, 17432
Offset: 1

Views

Author

Eric M. Schmidt, May 21 2013

Keywords

Crossrefs

Programs

  • Sage
    def A225929(q) : return q^2 + 2*q + (9 if q%6 in [1,5] else 8)

Formula

Let q be the n-th prime power. Then a(n) = q^2 + 2q + c, where c = 9 if q == 1, 5 (mod 6) and c = 8 otherwise.

A225937 Number of conjugacy classes in adjoint Chevalley group E_7(q) as q runs through the prime powers.

Original entry on oeis.org

531, 4569, 24553, 105644, 992834, 2447517, 5477205, 21674822, 68494004, 287617189, 437805224, 946620206, 3567305234, 6369359984, 10879403385, 17889596996, 28462405562, 35505127221, 97646355404, 199751157632, 278452165094, 517886829194, 692659723976
Offset: 1

Views

Author

Eric M. Schmidt, May 21 2013

Keywords

Crossrefs

Programs

  • Sage
    def A225937(q) : return q^7 + q^6 + 2*q^5 + (4*q^4 + 10*q^3 + 15*q^2 + 25*q + 21 if q%2==0 else 5*q^4 + 13*q^3 + 24*q^2 + 46*q + 57 if q%3==0 else 5*q^4 + 13*q^3 + 24*q^2 + 47*q + 59)

Formula

Let q be the n-th prime power. Then, a(n) is
q^7 + q^6 + 2q^5 + 4q^4 + 10q^3 + 15q^2 + 25q + 21 if q == 0 (mod 2);
q^7 + q^6 + 2q^5 + 5q^4 + 13q^3 + 24q^2 + 46q + 57 if q == 0 (mod 3);
q^7 + q^6 + 2q^5 + 5q^4 + 13q^3 + 24q^2 + 47q + 59 otherwise.

A195464 a(n) = 2^(4*n + 3) + 2*4^n + 3.

Original entry on oeis.org

13, 139, 2083, 32899, 524803, 8390659, 134225923, 2147516419, 34359869443, 549756338179, 8796095119363, 140737496743939, 2251799847239683, 36028797153181699, 576460752840294403, 9223372039002259459, 147573952598266347523, 2361183241469182345219
Offset: 0

Views

Author

Brad Clardy, Sep 19 2011

Keywords

Comments

Binary numbers of form 1j1i11 where j and i are the number of 0's, n is the index, i = 2*n+1, j = 2*n+3.

Examples

			Terms starting from n=1 written in binary are 10001011, 100000100011, 1000000010000011, 10000000001000000011.
		

Crossrefs

Cf. A188161.

Programs

Formula

a(n) = 2^(4*n+3) + A188161(n).
From Alexander R. Povolotsky, Sep 19 2011: (Start)
a(n+2) = 20*a(n+1) - 64*a(n) + 135.
G.f.: (-13 + 134*x - 256*x^2)/(-1 + 21*x - 84*x^2 + 64*x^3). (End)
a(n) = 3 + A026244(n+1). - Bruno Berselli, Sep 19 2011

A225930 Number of conjugacy classes in twisted Chevalley group 3D4(q) as q runs through the prime powers.

Original entry on oeis.org

35, 126, 345, 786, 2806, 4685, 7386, 16110, 30946, 69909, 88746, 137566, 292566, 406906, 551886, 732546, 954310, 1082405, 1926226, 2896410, 3500206, 4985766, 5884906, 8042226, 12326286, 14076610, 17043525, 20456446, 25774710, 28792666, 39449446, 43584810, 48037086
Offset: 1

Views

Author

Eric M. Schmidt, May 21 2013

Keywords

Crossrefs

Cf. A000961 (without 1), A188161, A224790, A225928-A225938.

Programs

  • Mathematica
    Map[(#^2 + 1)*(# + 1)*# + 5 + Mod[#, 2] &, Select[Range[100], PrimePowerQ]] (* Paolo Xausa, Jan 16 2025 *)
  • PARI
    apply(x->(x^4 + x^3 + x^2 + x + 5 + (x%2)), select(isprimepower, [1..100])) \\ Michel Marcus, Jan 16 2025

Formula

Let q be the n-th prime power. Then, a(n) = q^4 + q^3 + q^2 + q + c, where c = 5 if q is even and c = 6 if q is odd.

A225931 Number of conjugacy classes in Chevalley group F_4(q) as q runs through the prime powers.

Original entry on oeis.org

95, 273, 539, 1156, 3566, 5603, 8751, 18346, 34364, 75443, 95656, 146882, 308254, 426656, 576345, 762412, 990326, 1120595, 1985636, 2976016, 3591434, 5103526, 6017672, 8208724, 12553402, 14326796, 17326739, 20785106, 26163886, 29214704, 39981062, 44156775
Offset: 1

Views

Author

Eric M. Schmidt, May 21 2013

Keywords

Crossrefs

Programs

  • Sage
    def A225931(q) : return q^4 + 2*q^3 + (6*q^2 + 10*q + 19 if q%2==0 else 7*q^2 + 15*q + 30 if q%3==0 else 7*q^2 + 15*q + 31)

Formula

Let q be the n-th prime power.
a(n) = q^4 + 2q^3 + 6q^2 + 10q + 19 if q == 0 mod 2.
a(n) = q^4 + 2q^3 + 7q^2 + 15q + 30 if q == 0 mod 3.
a(n) = q^4 + 2q^3 + 7q^2 + 15q + 31 otherwise.

A225932 Number of conjugacy classes in simply connected Chevalley group E_6(q) as q runs through the prime powers.

Original entry on oeis.org

180, 1269, 6116, 20454, 140886, 304548, 605685, 1965462, 5262486, 17969012, 25736406, 49802214, 155060070, 254728710, 402876885, 616803846, 918054582, 1109465220, 2638941366, 4871761782, 6475396806, 11018543046, 14135564454, 22598655270, 42920128086
Offset: 1

Views

Author

Eric M. Schmidt, May 21 2013

Keywords

Crossrefs

Programs

  • Sage
    def A225932(q) : return q^6 + q^5 + 2*q^4 + 2*q^3 + [15*q^2 + 21*q + 60, 6*q^2 + 4*q + 4, 7*q^2 + 5*q + 3, 14*q^2 + 20*q + 52, 7*q^2 + 5*q + 4][q%6-1]

Formula

Let q be the n-th prime power.
a(n) = q^6 + q^5 + 2q^4 + 2q^3 + 15q^2 + 21q + 60 if q == 1 (mod 6).
a(n) = q^6 + q^5 + 2q^4 + 2q^3 + 6q^2 + 4q + 4 if q == 2 (mod 6).
a(n) = q^6 + q^5 + 2q^4 + 2q^3 + 7q^2 + 5q + 3 if q == 3 (mod 6).
a(n) = q^6 + q^5 + 2q^4 + 2q^3 + 14q^2 + 20q + 52 if q == 4 (mod 6).
a(n) = q^6 + q^5 + 2q^4 + 2q^3 + 7q^2 + 5q + 4 if q == 5 (mod 6).
Showing 1-10 of 14 results. Next