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 30 results. Next

A126646 a(n) = 2^(n+1) - 1.

Original entry on oeis.org

1, 3, 7, 15, 31, 63, 127, 255, 511, 1023, 2047, 4095, 8191, 16383, 32767, 65535, 131071, 262143, 524287, 1048575, 2097151, 4194303, 8388607, 16777215, 33554431, 67108863, 134217727, 268435455, 536870911, 1073741823, 2147483647
Offset: 0

Views

Author

Aleksandar M. Janjic and Milan Janjic, Feb 08 2007, Feb 13 2007

Keywords

Comments

a(n) is the number of integers k less than 10^n such that the decimal representation of k lacks the digits 1,2,3,4,5,6 and 7 and at least one of the digits 8,9.
Partial sums of the powers of 2 (A000079).
a(n) is the number of elements (all m-dimensional faces) in an n-dimensional simplex (0 <= m <= n). - Sergey Pavlov, Aug 15 2015
A261461(a(n)) != A261922(a(n)). - Reinhard Zumkeller, Sep 17 2015
a(n) is the total number of matches in a knockout tournament with 2^n players. - Paul Duckett, Dec 12 2022

Examples

			a(8) = 2^9 - 1 = 511.
		

Crossrefs

Programs

Formula

a(n-1)^2 + a(n) = a(2n) + 1, a square. - Vincenzo Librandi and Ralf Stephan, Nov 23 2010
G.f.: 1/ ( (1-2*x)*(1-x) ). - R. J. Mathar, Dec 02 2013
a(n) = 3*a(n-1) - 2*a(n-2), n > 1. - Wesley Ivan Hurt, Aug 21 2015
E.g.f.: 2*exp(2*x) - exp(x). - G. C. Greubel, Mar 31 2021

A125858 a(n) is the number of nonnegative integers k less than 10^n such that the decimal representation of k lacks at least one of digits 1,2,3,4,5,6,7,8,9.

Original entry on oeis.org

10, 100, 1000, 10000, 100000, 1000000, 10000000, 100000000, 999637120, 9980041600, 99381289600, 985729744000, 9726841354240, 95404977568000, 929690189228800, 8999055703648000, 86532737999167360, 826798452380099200, 7852626768025993600
Offset: 1

Views

Author

Aleksandar M. Janjic and Milan Janjic, Feb 03 2007

Keywords

Comments

Note that the first eight terms of the sequence are powers of 10.

Crossrefs

Cf. A125630.

Programs

  • Maple
    f:=n->9*9^n-36*8^n+84*7^n-126*6^n+126*5^n-84*4^n+36*3^n-9*2^n+1;
  • Mathematica
    f[n_] := (9*9^n - 36*8^n + 84*7^n - 126*6^n + 126*5^n - 84*4^n + 36*3^n - 9*2^n + 1); Array[f, 18] (* Robert G. Wilson v, May 31 2009 *)
    (* or *) f[n_] := Sum[ -(-1)^k*Binomial[9, k] (10 - k)^n, {k, 9}]; Array[f, 18] (* Robert G. Wilson v, May 31 2009 *)
  • PARI
    vector(100, n, 9*9^n-36*8^n+84*7^n-126*6^n+126*5^n-84*4^n+36*3^n-9*2^n+1) \\ Colin Barker, Feb 23 2015

Formula

a(n) = 9*9^n-36*8^n+84*7^n-126*6^n+126*5^n-84*4^n+36*3^n-9*2^n+1.

Extensions

Incorrect g.f. removed by Georg Fischer, May 15 2019

A125880 a(n) is the number of nonnegative integers k less than 10^n such that the decimal representation of k lacks at least one of the digits 1,2 and at least one of the digits 3,4,5,6,7,8,9.

Original entry on oeis.org

10, 98, 946, 9026, 85330, 800738, 7463746, 69054146, 633214450, 5746812578, 51574432546, 457575310466, 4014480866770, 34850492651618, 299615359353346, 2553264555537986, 21587837904314290, 181256003521421858, 1512536914179602146, 12553861394003656706
Offset: 1

Views

Author

Aleksandar M. Janjic and Milan Janjic, Feb 03 2007, Feb 13 2007

Keywords

Crossrefs

Cf. A125630.

Programs

  • Maple
    f:=n->14*8^n-49*7^n+91*6^n-105*5^n+77*4^n-35*3^n+9*2^n-1;
  • Mathematica
    Table[14*8^n-49*7^n+91*6^n-105*5^n+77*4^n-35*3^n+9*2^n-1,{n,20}] (* James C. McMahon, Dec 22 2024 *)
  • PARI
    vector(100, n, 14*8^n-49*7^n+91*6^n-105*5^n+77*4^n-35*3^n+9*2^n-1) \\ Colin Barker, Feb 23 2015

Formula

a(n) = 14*8^n-49*7^n+91*6^n-105*5^n+77*4^n-35*3^n+9*2^n-1.
G.f.: -2*x*(20160*x^7 -54792*x^6 +53420*x^5 -28436*x^4 +8441*x^3 -1439*x^2 +131*x -5) / ((x -1)*(2*x -1)*(3*x -1)*(4*x -1)*(5*x -1)*(6*x -1)*(7*x -1)*(8*x -1)). - Colin Barker, Feb 23 2015

A125904 a(n) is the number of nonnegative integers k less than 10^n such that the decimal representation of k lacks at least one of the digits 1,2,3,4 and at least one of the digits 5,6,7,8,9.

Original entry on oeis.org

10, 100, 1000, 9976, 98920, 971440, 9420400, 90005176, 846101080, 7822770880, 71163913600, 637585923976, 5633160763240, 49148451899920, 424055315011600, 3623013325068376, 30689130457473400, 258015134469182560, 2155143129458730400
Offset: 1

Views

Author

Aleksandar M. Janjic and Milan Janjic, Feb 03 2007

Keywords

Crossrefs

Cf. A125630.

Programs

  • Maple
    f:=n->20*8^n-70*7^n+120*6^n-125*5^n+84*4^n-36*3^n+9*2^n-1;
  • PARI
    vector(100, n, 20*8^n-70*7^n+120*6^n-125*5^n+84*4^n-36*3^n+9*2^n-1) \\ Colin Barker, Feb 23 2015

Formula

a(n) = 20*8^n-70*7^n+120*6^n-125*5^n+84*4^n-36*3^n+9*2^n-1.
G.f.: -2*x*(20160*x^7 -54792*x^6 +53362*x^5 -28337*x^4 +8392*x^3 -1430*x^2 +130*x -5) / ((x -1)*(2*x -1)*(3*x -1)*(4*x -1)*(5*x -1)*(6*x -1)*(7*x -1)*(8*x -1)). - Colin Barker, Feb 23 2015

A125908 a(n) is the number of nonnegative integers k less than 10^n such that the decimal representation of k lacks the digits 1 and 2 and at least one of digits 3,4,5,6,7,8,9.

Original entry on oeis.org

8, 64, 512, 4096, 32768, 262144, 2092112, 16595776, 130437728, 1013866624, 7788438512, 59145432256, 444357721088, 3306242197504, 24389881261712, 178578361769536, 1299058046034848, 9397253451942784, 67653687455953712, 485065987257543616
Offset: 1

Views

Author

Aleksandar M. Janjic and Milan Janjic, Feb 04 2007

Keywords

Examples

			a(8) = 16595776.
		

Crossrefs

Cf. A125630.

Programs

  • Maple
    f:=n->7*7^n-21*6^n+35*5^n-35*4^n+21*3^n-7*2^n+1;
  • PARI
    Vec(-8*x*(630*x^6-1476*x^5+1457*x^4-664*x^3+162*x^2-20*x+1)/((x-1)*(2*x-1)*(3*x-1)*(4*x-1)*(5*x-1)*(6*x-1)*(7*x-1)) + O(x^100)) \\ Colin Barker, Feb 22 2015

Formula

a(n) = 7*7^n-21*6^n+35*5^n-35*4^n+21*3^n-7*2^n+1.
G.f.: -8*x*(630*x^6 -1476*x^5 +1457*x^4 -664*x^3 +162*x^2 -20*x +1)/((x -1)*(2*x -1)*(3*x -1)*(4*x -1)*(5*x -1)*(6*x -1)*(7*x -1)). - Colin Barker, Feb 22 2015

A125909 a(n) is the number of nonnegative integers k less than 10^n such that the decimal representation of k lacks the digit 1, at least one of the digits 2,3 and at least one of digits 4,5,6,7,8,9.

Original entry on oeis.org

9, 79, 681, 5791, 48729, 405919, 3340521, 27094111, 216288249, 1699187359, 13147825161, 100334472031, 756309350169, 5639967562399, 41669245538601, 305413957523551, 2223312590034489, 16091187568891039, 115885120813664841, 831075819022712671
Offset: 1

Views

Author

Aleksandar M. Janjic and Milan Janjic, Feb 04 2007

Keywords

Crossrefs

Cf. A125630.

Programs

  • Maple
    f:=n->12*7^n-36*6^n+55*5^n-50*4^n+27*3^n-8*2^n+1;
  • PARI
    Vec(-x*(5040*x^6 -11988*x^5 +11944*x^4 -5479*x^3 +1367*x^2 -173*x+9) / ((x -1)*(2*x -1)*(3*x -1)*(4*x -1)*(5*x -1)*(6*x -1)*(7*x -1)) + O(x^100)) \\ Colin Barker, Feb 22 2015

Formula

a(n) = 12*7^n-36*6^n+55*5^n-50*4^n+27*3^n-8*2^n+1.
G.f.: -x*(5040*x^6 -11988*x^5 +11944*x^4 -5479*x^3 +1367*x^2 -173*x+9) / ((x -1)*(2*x -1)*(3*x -1)*(4*x -1)*(5*x -1)*(6*x -1)*(7*x -1)). - Colin Barker, Feb 22 2015

A125945 a(n) is the number of nonnegative integers k less than 10^n such that the decimal representation of k lacks at least one of digits 1,2, at least one of digits 3,4 and at least one of digits 5,6,7,8,9.

Original entry on oeis.org

10, 96, 892, 8076, 71500, 619236, 5241652, 43355436, 350740540, 2780210676, 21641505412, 165814383996, 1253254845580, 9362782430916, 69259450905172, 508062802935756, 3700662365318620, 26794126632247956, 193018363703408932, 1384505203965202716
Offset: 1

Views

Author

Aleksandar M. Janjic and Milan Janjic, Feb 04 2007

Keywords

Crossrefs

Cf. A125630.

Programs

  • Maple
    f:=n->20*7^n-60*6^n+85*5^n-70*4^n+34*3^n-9*2^n+1;
  • PARI
    a(n)=20*7^n-60*6^n+85*5^n-70*4^n+34*3^n-9*2^n+1 \\ Charles R Greathouse IV, Sep 24 2015

Formula

a(n) = 20*7^n-60*6^n+85*5^n-70*4^n+34*3^n-9*2^n+1.
G.f.: -2*x*(2520*x^6 -6054*x^5 +6063*x^4 -2794*x^3 +712*x^2 -92*x +5) / ((x -1)*(2*x -1)*(3*x -1)*(4*x -1)*(5*x -1)*(6*x -1)*(7*x -1)). - Colin Barker, Feb 23 2015

A125947 a(n) is the number of nonnegative integers k less than 10^n such that the decimal representation of k lacks the digit 1, at least one of digits 2,3,4,5 and at least one of digits 6,7,8,9.

Original entry on oeis.org

9, 81, 729, 6513, 57369, 495921, 4194969, 34689393, 280607769, 2224214961, 17313344409, 132651929073, 1002605145369, 7490229758001, 55407572177049, 406450276733553, 2960529995462169, 21435301615525041, 154414691892116889, 1107604165960750833
Offset: 1

Views

Author

Aleksandar M. Janjic and Milan Janjic, Feb 04 2007

Keywords

Examples

			a(8) = 34689393.
		

Crossrefs

Cf. A125630.

Programs

  • Maple
    f:=n->16*7^n-48*6^n+68*5^n-56*4^n+28*3^n-8*2^n+1;
  • Mathematica
    Table[ 16*7^n-48*6^n+68*5^n-56*4^n+28*3^n-8*2^n+1, {n, 20}] (* James C. McMahon, Dec 23 2024 *)
  • PARI
    Vec(-3*x*(1680*x^6 -3988*x^5 +3968*x^4 -1819*x^3 +453*x^2-57*x+3) / ((x -1)*(2*x -1)*(3*x -1)*(4*x -1)*(5*x -1)*(6*x -1)*(7*x -1)) + O(x^100)) \\ Colin Barker, Feb 22 2015

Formula

a(n) = 16*7^n-48*6^n+68*5^n-56*4^n+28*3^n-8*2^n+1.
G.f.: -3*x*(1680*x^6 -3988*x^5 +3968*x^4 -1819*x^3 +453*x^2-57*x+3) / ((x -1)*(2*x -1)*(3*x -1)*(4*x -1)*(5*x -1)*(6*x -1)*(7*x -1)). - Colin Barker, Feb 22 2015

A125948 a(n) is the number of nonnegative integers k less than 10^n such that the decimal representation of k lacks at least one of digits 1,2,3, at least one of digits 4,5,6 and at least one of digits 7,8,9.

Original entry on oeis.org

10, 100, 982, 9388, 86950, 778780, 6748822, 56713708, 463661830, 3700940860, 28941318262, 222422713228, 1684544507110, 12602134130140, 93308618633302, 684912371803948, 4990975002030790, 36147245625290620, 260449744313893942
Offset: 1

Views

Author

Aleksandar M. Janjic and Milan Janjic, Feb 04 2007

Keywords

Crossrefs

Cf. A125630.

Programs

  • Maple
    f:=n->27*7^n-81*6^n+108*5^n-81*4^n+36*3^n-9*2^n+1;
  • Mathematica
    Table[27*7^n-81*6^n+108*5^n-81*4^n+36*3^n-9*2^n+1,{n,19}] (* James C. McMahon, Dec 23 2024 *)
  • PARI
    vector(100, n, 27*7^n-81*6^n+108*5^n-81*4^n+36*3^n-9*2^n+1) \\ Colin Barker, Feb 23 2015

Formula

a(n) = 27*7^n-81*6^n+108*5^n-81*4^n+36*3^n-9*2^n+1.
G.f.: -2*x*(2520*x^6 -6012*x^5 +5990*x^4 -2754*x^3 +701*x^2 -90*x +5) / ((x -1)*(2*x -1)*(3*x -1)*(4*x -1)*(5*x -1)*(6*x -1)*(7*x -1)). - Colin Barker, Feb 23 2015

A125897 a(n) is the number of nonnegative integers k less than 10^n such that the decimal representation of k lacks at least one of the digits 1,2,3 and at least one of the digits 4,5,6,7,8,9.

Original entry on oeis.org

10, 100, 994, 9796, 95650, 924820, 8845714, 83575396, 778945090, 7156197940, 64800104434, 578648865796, 5100362368930, 44424892053460, 382839350691154, 3268062540952996, 27665402010407170, 232490197792427380, 1941315874498269874
Offset: 1

Views

Author

Aleksandar M. Janjic and Milan Janjic, Feb 03 2007

Keywords

Crossrefs

Cf. A125630.

Programs

  • Maple
    f:=n->18*8^n-63*7^n+111*6^n-120*5^n+83*4^n-36*3^n+9*2^n-1;
  • Mathematica
    Table[18*8^n-63*7^n+111*6^n-120*5^n+83*4^n-36*3^n+9*2^n-1, {n, 19}]  (* James C. McMahon, Dec 22 2024 *)
  • PARI
    vector(100, n, 18*8^n-63*7^n+111*6^n-120*5^n+83*4^n-36*3^n+9*2^n-1) \\ Colin Barker, Feb 23 2015

Formula

a(n) = 18*8^n-63*7^n+111*6^n-120*5^n+83*4^n-36*3^n+9*2^n-1.
G.f.: -2*x*(20160*x^7 -54792*x^6 +53344*x^5 -28304*x^4 +8374*x^3 -1427*x^2 +130*x -5) / ((x -1)*(2*x -1)*(3*x -1)*(4*x -1)*(5*x -1)*(6*x -1)*(7*x -1)*(8*x -1)). - Colin Barker, Feb 23 2015
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