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.

Previous Showing 11-20 of 20 results.

A104896 a(0) = 0; a(n) = 7*a(n-1) + 7.

Original entry on oeis.org

0, 7, 56, 399, 2800, 19607, 137256, 960799, 6725600, 47079207, 329554456, 2306881199, 16148168400, 113037178807, 791260251656, 5538821761599, 38771752331200, 271402266318407, 1899815864228856, 13298711049601999, 93090977347214000, 651636841430498007
Offset: 0

Views

Author

Alexandre Wajnberg, Apr 24 2005

Keywords

Comments

Conjecture: this is also the number of integers from 0 to 10^n - 1 that lack 0, 1 and 2 as a digit.
Number of monic irreducible polynomials of degree 1 in GF(7)[x1,...,xn]. - Max Alekseyev, Jan 23 2006

Crossrefs

Programs

  • Magma
    [(7/6)*(7^n -1): n in [0..30]]; // G. C. Greubel, Jun 09 2021
    
  • Maple
    a:=n->sum (7^j,j=1..n): seq(a(n), n=0..30); # Zerinvary Lajos, Oct 03 2007
  • Mathematica
    RecurrenceTable[{a[n]==7*a[n-1]+7,a[0]==0},a,{n,0,30}] (* Vaclav Kotesovec, Jul 25 2014 *)
  • PARI
    concat(0, Vec(7*x/((x-1)*(7*x-1)) + O(x^30))) \\ Colin Barker, Jul 25 2014
    
  • Sage
    [(7/6)*(7^n -1) for n in (0..30)] # G. C. Greubel, Jun 09 2021

Formula

a(n) = (7^(n+1) - 7) / 6. - Max Alekseyev, Jan 23 2006
a(n) = a(n-1) + 7^n with a(0)=0. - Vincenzo Librandi, Nov 13 2010
From Colin Barker, Jul 25 2014: (Start)
a(n) = 8*a(n-1) - 7*a(n-2).
G.f.: 7*x / ((x-1)*(7*x-1)). (End)
E.g.f.: (7/6)*(exp(7*x) - exp(x)). - G. C. Greubel, Jun 09 2021

A105281 a(0)=0; a(n) = 6*a(n-1) + 6.

Original entry on oeis.org

0, 6, 42, 258, 1554, 9330, 55986, 335922, 2015538, 12093234, 72559410, 435356466, 2612138802, 15672832818, 94036996914, 564221981490, 3385331888946, 20311991333682, 121871948002098, 731231688012594, 4387390128075570, 26324340768453426, 157946044610720562
Offset: 0

Views

Author

Alexandre Wajnberg, Apr 25 2005

Keywords

Comments

Number of integers from 0 to (10^n) - 1 that lack 0, 1, 2 and 3 as a digit.
a(n) is the expected number of tosses of a single die needed to obtain for the first time a string of n consecutive 6's. - Jean M. Morales, Aug 04 2012

Crossrefs

Programs

  • Maple
    a:=n->add(6^j,j=1..n): seq(a(n),n=0..30); # Zerinvary Lajos, Oct 03 2007
  • Mathematica
    NestList[6#+6&,0,30] (* Harvey P. Dale, Jul 24 2012 *)
  • PARI
    a(n)=if(n<0,0, (6^n-1)*6/5)

Formula

a(n) = 6^n + a(n-1) (with a(0)=0). - Vincenzo Librandi, Nov 13 2010
From Colin Barker, Jan 28 2013: (Start)
a(n) = 7*a(n-1) - 6*a(n-2).
G.f.: 6*x/((x-1)*(6*x-1)). (End)
From Elmo R. Oliveira, Mar 16 2025: (Start)
E.g.f.: 6*exp(x)*(exp(5*x) - 1)/5.
a(n) = 6*(6^n - 1)/5.
a(n) = 6*A003464(n). (End)

Extensions

More terms from Harvey P. Dale, Jul 24 2012

A228250 Total sum A(n,k) of lengths of longest contiguous subsequences with the same value over all s in {1,...,n}^k; square array A(n,k), n>=0, k>=0, read by antidiagonals.

Original entry on oeis.org

0, 0, 0, 0, 1, 0, 0, 2, 2, 0, 0, 3, 6, 3, 0, 0, 4, 16, 12, 4, 0, 0, 5, 38, 45, 20, 5, 0, 0, 6, 86, 156, 96, 30, 6, 0, 0, 7, 188, 519, 436, 175, 42, 7, 0, 0, 8, 404, 1680, 1916, 980, 288, 56, 8, 0, 0, 9, 856, 5349, 8232, 5345, 1914, 441, 72, 9, 0
Offset: 0

Views

Author

Alois P. Heinz, Aug 18 2013

Keywords

Examples

			A(4,1) = 4 = 1+1+1+1: [1], [2], [3], [4].
A(1,4) = 4: [1,1,1,1].
A(3,2) = 12 = 2+1+1+1+2+1+1+1+2: [1,1], [1,2], [1,3], [2,1], [2,2], [2,3], [3,1], [3,2], [3,3].
A(2,3) = 16 = 3+2+1+2+2+1+2+3: [1,1,1], [1,1,2], [1,2,1], [1,2,2], [2,1,1], [2,1,2], [2,2,1], [2,2,2].
Square array A(n,k) begins:
  0, 0,  0,   0,    0,     0,      0,       0, ...
  0, 1,  2,   3,    4,     5,      6,       7, ...
  0, 2,  6,  16,   38,    86,    188,     404, ...
  0, 3, 12,  45,  156,   519,   1680,    5349, ...
  0, 4, 20,  96,  436,  1916,   8232,   34840, ...
  0, 5, 30, 175,  980,  5345,  28610,  151115, ...
  0, 6, 42, 288, 1914, 12450,  79716,  504492, ...
  0, 7, 56, 441, 3388, 25571, 190428, 1403689, ...
		

Crossrefs

Columns k=0-3 give: A000004, A001477, A002378, A152618(n+1).
Rows n=0-2 give: A000004, A001477, 2*A102712.
Main diagonal gives: A228194.
Cf. A228275.

Programs

  • Maple
    b:= proc(n, m, s, i) option remember; `if`(m>i or s>m, 0,
          `if`(i=0, 1, `if`(i=1, n, `if`(s=1, (n-1)*add(
             b(n, m, h, i-1), h=1..m), b(n, m, s-1, i-1)+
          `if`(s=m, b(n, m-1, s-1, i-1), 0)))))
        end:
    A:= (n, k)-> add(m*add(b(n, m, s, k), s=1..m), m=1..k):
    seq(seq(A(n, d-n), n=0..d), d=0..12);
  • Mathematica
    b[n_, m_, s_, i_] := b[n, m, s, i] = If[m>i || s>m, 0, If[i == 0, 1, If[i == 1, n, If[s == 1, (n-1)*Sum[b[n, m, h, i-1], {h, 1, m}], b[n, m, s-1, i-1] + If[s == m, b[n, m-1, s-1, i-1], 0]]]]]; A[n_, k_] := Sum[m*Sum[b[n, m, s, k], {s, 1, m}], {m, 1, k}]; Table[Table[A[n, d-n], {n, 0, d}], {d, 0, 12}] // Flatten (* Jean-François Alcover, Jan 19 2015, after Alois P. Heinz *)

A105280 a(0)=0; a(n) = 11*a(n-1) + 11.

Original entry on oeis.org

0, 11, 132, 1463, 16104, 177155, 1948716, 21435887, 235794768, 2593742459, 28531167060, 313842837671, 3452271214392, 37974983358323, 417724816941564, 4594972986357215, 50544702849929376, 555991731349223147, 6115909044841454628, 67274999493256000919, 740024994425816010120
Offset: 0

Views

Author

Alexandre Wajnberg, Apr 25 2005

Keywords

Crossrefs

Programs

  • Maple
    a:=n-> add(11^j,j=1..n): seq(a(n),n=0..12); # Zerinvary Lajos, Oct 03 2007
  • Mathematica
    NestList[11#+11&,0,20] (* or *) LinearRecurrence[{12,-11},{0,11},20] (* Harvey P. Dale, Dec 02 2023 *)

Formula

a(n) = 11^n + a(n-1) (with a(0)=0). - Vincenzo Librandi, Nov 13 2010
From Elmo R. Oliveira, May 24 2025: (Start)
G.f.: 11*x/((x-1)*(11*x-1)).
E.g.f.: 11*exp(x)*(exp(10*x) - 1)/10.
a(n) = 11*(11^n - 1)/10.
a(n) = 12*a(n-1) - 11*a(n-2).
a(n) = A016123(n) - 1. (End)

Extensions

Corrected by T. D. Noe, Nov 07 2006

A125120 Sum of values of repunits of length n in base b representation with 1

Original entry on oeis.org

1, 7, 41, 296, 2829, 34637, 519049, 9197344, 188039787, 4356087231, 112754069273, 3224945523736, 100999970565337, 3437517630509497, 126332966608699441, 4986057436997869696, 210331809309776028055, 9443995455881145458715
Offset: 1

Views

Author

Reinhard Zumkeller, Nov 21 2006

Keywords

Examples

			a(4) = [1111]_2 + [1111]_3 + [1111]_4 + [1111]_5 = ((2+1)*2+1)*2+1 + ((3+1)*3+1)*3+1 + ((4+1)*4+1)*4+1 + ((5+1)*5+1)*5+1 = 296.
		

Crossrefs

Row sums of A125118.

Programs

  • Magma
    [(&+[(k^n -1)/(k-1): k in [2..n+1]]) : n in [1..30]]; // G. C. Greubel, Aug 14 2022
    
  • Mathematica
    Table[Sum[(k^n -1)/(k-1), {k, 2, n+1}], {n, 30}] (* G. C. Greubel, Aug 14 2022 *)
  • PARI
    a(n) = sum(k=1, n, sum(i=0, n-1, (k+1)^i)); \\ Michel Marcus, Dec 14 2020
    
  • SageMath
    [sum(((k+1)^n -1)/k for k in (1..n)) for n in (1..30)] # G. C. Greubel, Aug 14 2022

Formula

a(n) = Sum_{k=1..n} Sum_{i=0..n-1} (k+1)^i. [Corrected by Mathew Englander, Dec 14 2020]
a(n) = Sum_{k=1..n} A125118(n,k).
a(n+1) - a(n) = A076015(n+1) + A228275(n+2, n). - Mathew Englander, Dec 14 2020
a(n) = Sum_{j=2..n+1} (j^n - 1)/(j-1)

A228290 a(n) = n^6 + n^5 + n^4 + n^3 + n^2 + n.

Original entry on oeis.org

0, 6, 126, 1092, 5460, 19530, 55986, 137256, 299592, 597870, 1111110, 1948716, 3257436, 5229042, 8108730, 12204240, 17895696, 25646166, 36012942, 49659540, 67368420, 90054426, 118778946, 154764792, 199411800, 254313150, 321272406, 402321276, 499738092
Offset: 0

Views

Author

Alois P. Heinz, Aug 19 2013

Keywords

Crossrefs

Column k=6 of A228275.

Programs

  • Maple
    a:= n-> (1+(1+(1+(1+(1+n)*n)*n)*n)*n)*n:
    seq(a(n), n=0..30);
    # second Maple program:
    a:= proc(n) option remember; `if`(n<2, 6*n,
          (n+1)*(n^2+n+1)*a(n-1)/((n-1)*(n^2-3*n+3)))
        end:
    seq(a(n), n=0..30);
    # third Maple program:
    a:= n-> `if`(n=1, 6, (n^7-n)/(n-1)):
    seq(a(n), n=0..30);
  • PARI
    a(n) = n^6 + n^5 + n^4 + n^3 + n^2 + n; \\ Joerg Arndt, Sep 03 2013
  • R
    a <- c(0, 6, 126, 1092, 5460, 19530, 55986)
    for(n in (length(a)+1):30) a[n] <- 7*a[n-1] -21*a[n-2] +35*a[n-3] -35*a[n-4] +21*a[n-5] -7*a[n-6] +a[n-7]
    a
    [Yosu Yurramendi, Sep 03 2013]
    

Formula

G.f.: -6*x*(7*x^4+42*x^3+56*x^2+14*x+1)/(x-1)^7.
a(n) = (n+1)*(n^2+n+1)*a(n-1)/((n-1)*(n^2-3*n+3)) for n>1.
a(1) = 6, else a(n) = (n^7-n)/(n-1).
a(n) = 6*A059721(n) = n*(n+1)*(1+n+n^2)*(1-n+n^2). - R. J. Mathar, Aug 21 2013
a(n) = 7*a(n-1) -21*a(n-2) +35*a(n-3) -35*a(n-4) +21*a(n-5) -7*a(n-6) +a(n-7) for n>6, a(0)=0, a(1)=6, a(2)=126, a(3)=1092, a(4)=5460, a(5)=19530, a(6)=55986. - Yosu Yurramendi, Sep 03 2013

A228291 a(n) = Sum_{k=1..7} n^k.

Original entry on oeis.org

0, 7, 254, 3279, 21844, 97655, 335922, 960799, 2396744, 5380839, 11111110, 21435887, 39089244, 67977559, 113522234, 183063615, 286331152, 435984839, 648232974, 943531279, 1347368420, 1891142967, 2613136834, 3559590239, 4785883224, 6357828775, 8353082582
Offset: 0

Views

Author

Alois P. Heinz, Aug 19 2013

Keywords

Crossrefs

Column k=7 of A228275.

Programs

  • Maple
    a:= n-> `if`(n=1, 7, (n^8-n)/(n-1)):
    seq(a(n), n=0..30);
  • Mathematica
    Table[Total[n^Range[7]],{n,0,30}] (* or *) LinearRecurrence[{8,-28,56,-70,56,-28,8,-1},{0,7,254,3279,21844,97655,335922,960799},30] (* Harvey P. Dale, Dec 06 2018 *)
  • R
    a <- c(0, 7, 254, 3279, 21844, 97655, 335922, 960799)
    for(n in (length(a)+1):30) a[n] <- 8*a[n-1] -28*a[n-2] +56*a[n-3] -70*a[n-4] +56*a[n-5] -28*a[n-6] +8*a[n-7] -a[n-8]
    a  [Yosu Yurramendi, Sep 03 2013]

Formula

G.f.: x*(x^6+78*x^5+981*x^4+2332*x^3+1443*x^2+198*x+7)/(x-1)^8.
a(1) = 7, else a(n) = (n^8-n)/(n-1).
a(n) = 8*a(n-1) - 28*a(n-2) + 56*a(n-3) - 70*a(n-4) + 56*a(n-5) - 28*a(n-6) + 8*a(n-7) - a(n-8) with n > 7, a(0)=0, a(1)=7, a(2)=254, a(3)=3279, a(4)=21844, a(5)=97655, a(6)=335922, a(7)=960799. - Yosu Yurramendi, Sep 03 2013

A228292 a(n) = Sum_{k=1..8} n^k.

Original entry on oeis.org

0, 8, 510, 9840, 87380, 488280, 2015538, 6725600, 19173960, 48427560, 111111110, 235794768, 469070940, 883708280, 1589311290, 2745954240, 4581298448, 7411742280, 11668193550, 17927094320, 26947368420, 39714002328, 57489010370, 81870575520, 114861197400
Offset: 0

Views

Author

Alois P. Heinz, Aug 19 2013

Keywords

Crossrefs

Column k=8 of A228275.

Programs

  • Maple
    a:= n-> `if`(n=1, 8, (n^9-n)/(n-1)):
    seq(a(n), n=0..30);
  • Mathematica
    Table[Total[n^Range[8]],{n,0,30}] (* or *) LinearRecurrence[ {9,-36,84,-126,126,-84,36,-9,1},{0,8,510,9840,87380,488280,2015538,6725600,19173960},30] (* Harvey P. Dale, Jan 28 2014 *)

Formula

G.f.: -2*x*(85*x^6+1695*x^5+7134*x^4+8254*x^3+2769*x^2+219*x+4)/(x-1)^9.
a(1) = 8, else a(n) = (n^9-n)/(n-1).
a(0)=0, a(1)=8, a(2)=510, a(3)=9840, a(4)=87380, a(5)=488280, a(6)=2015538, a(7)=6725600, a(8)=19173960, a(n)=9*a(n-1)-36*a(n-2)+84*a(n-3)- 126*a(n-4)+ 126*a(n-5)- 84*a(n-6)+36*a(n-7)-9*a(n-8)+a(n-9). - Harvey P. Dale, Jan 28 2014

A228293 a(n) = Sum_{k=1..9} n^k.

Original entry on oeis.org

0, 9, 1022, 29523, 349524, 2441405, 12093234, 47079207, 153391688, 435848049, 1111111110, 2593742459, 5628851292, 11488207653, 22250358074, 41189313615, 73300775184, 125999618777, 210027483918, 340614792099, 538947368420, 833994048909, 1264758228162
Offset: 0

Views

Author

Alois P. Heinz, Aug 19 2013

Keywords

Crossrefs

Column k=9 of A228275.

Programs

  • Maple
    a:= n-> `if`(n=1, 9, (n^10-n)/(n-1)):
    seq(a(n), n=0..30);
  • Mathematica
    Table[Total[n^Range[9]],{n,0,30}] (* or *) LinearRecurrence[ {10, -45, 120, -210, 252, -210, 120, -45, 10, -1}, {0,9,1022,29523, 349524, 2441405, 12093234,47079207,153391688,435848049},30] (* Harvey P. Dale, Dec 12 2013 *)

Formula

G.f.: x*(x^8 +332*x^7 +11388*x^6 +77356*x^5 +153950*x^4 +99204*x^3 +19708*x^2 +932*x+9) / (x-1)^10.
a(1) = 9, else a(n) = (n^10-n)/(n-1).
a(0)=0, a(1)=9, a(2)=1022, a(3)=29523, a(4)=349524, a(5)=2441405, a(6)=12093234, a(7)=47079207, a(8)=153391688, a(9)=435848049, a(n) = 10*a(n-1) -45*a(n-2) +120*a(n-3) -210*a(n-4) +252*a(n-5) -210*a(n-6) +120*a(n-7) -45*a(n-8) +10*a(n-9) -a(n-10). - Harvey P. Dale, Dec 12 2013

A228294 a(n) = Sum_{k=1..10} n^k.

Original entry on oeis.org

0, 10, 2046, 88572, 1398100, 12207030, 72559410, 329554456, 1227133512, 3922632450, 11111111110, 28531167060, 67546215516, 149346699502, 311505013050, 617839704240, 1172812402960, 2141993519226, 3780494710542, 6471681049900, 10778947368420, 17513875027110
Offset: 0

Views

Author

Alois P. Heinz, Aug 19 2013

Keywords

Crossrefs

Column k=10 of A228275.

Programs

  • Maple
    a:= n-> `if`(n=1, 10, (n^11-n)/(n-1)):
    seq(a(n), n=0..30);
  • Mathematica
    Table[Total[n^Range[10]],{n,0,30}] (* Harvey P. Dale, May 14 2014 *)

Formula

G.f.: -2*x*(341*x^8 +18392*x^7 +194612*x^6 +616880*x^5 +682550*x^4 +267344*x^3 +33308*x^2 +968*x+5) / (x-1)^11.
a(1) = 10, else a(n) = (n^11-n)/(n-1).
Previous Showing 11-20 of 20 results.