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 11-16 of 16 results.

A175165 a(n) = 32*(2^n - 1).

Original entry on oeis.org

0, 32, 96, 224, 480, 992, 2016, 4064, 8160, 16352, 32736, 65504, 131040, 262112, 524256, 1048544, 2097120, 4194272, 8388576, 16777184, 33554400, 67108832, 134217696, 268435424, 536870880
Offset: 0

Views

Author

Reinhard Zumkeller, Feb 28 2010

Keywords

Crossrefs

Sequences of the form m*(2^n - 1): A000225 (m=1), A000918 (m=2), A068156 (m=3), A028399 (m=4), A068293 (m=6), A159741 (m=8), A175164 (m=16), this sequence (m=32), A175166 (m=64).
Cf. A173787.

Programs

  • Magma
    I:=[0,32]; [n le 2 select I[n] else 3*Self(n-1) - 2*Self(n-2): n in [1..41]]; // G. C. Greubel, Jul 08 2021
    
  • Mathematica
    32(2^Range[0,30] -1) (* or *) LinearRecurrence[{3,-2},{0,32},30] (* Harvey P. Dale, Mar 23 2015 *)
  • Python
    def A175165(n): return (1<Chai Wah Wu, Jun 27 2023
  • Sage
    [32*(2^n -1) for n in (0..40)] # G. C. Greubel, Jul 08 2021
    

Formula

a(n) = 2^(n+5) - 32.
a(n) = A173787(n+5, 5).
a(n) = 3*a(n-1) - 2*a(n-2); a(0)=0, a(1)=32. - Vincenzo Librandi, Dec 28 2010
From G. C. Greubel, Jul 08 2021: (Start)
G.f.: 32*x/((1-x)*(1-2*x)).
E.g.f.: 32*(exp(2*x) - exp(x)). (End)

A161770 n 1's followed by three 0's.

Original entry on oeis.org

1000, 11000, 111000, 1111000, 11111000, 111111000, 1111111000, 11111111000, 111111111000, 1111111111000, 11111111111000, 111111111111000, 1111111111111000, 11111111111111000, 111111111111111000, 1111111111111111000, 11111111111111111000, 111111111111111111000
Offset: 1

Views

Author

Jaroslav Krizek, Jun 18 2009

Keywords

Comments

Sequence A159741 written in base 2.

Crossrefs

Programs

  • Mathematica
    Table[FromDigits[PadLeft[{0,0,0},n,1]],{n,4,20}] (* Harvey P. Dale, Aug 07 2023 *)

Formula

a(n) = 1000*(10^n - 1)/9 = 1000*A002275(n).
G.f.: 1000*x/((10*x-1)*(x-1)).
From Elmo R. Oliveira, Jun 18 2025: (Start)
E.g.f.: 1000*exp(x)*(exp(9*x) - 1)/9.
a(n) = 100*A105279(n) = 10*A124166(n).
a(n) = 11*a(n-1) - 10*a(n-2) for n > 2. (End)

Extensions

Edited by Charles R Greathouse IV, Oct 12 2009

A246168 a(n) = 2^n - 10.

Original entry on oeis.org

-9, -8, -6, -2, 6, 22, 54, 118, 246, 502, 1014, 2038, 4086, 8182, 16374, 32758, 65526, 131062, 262134, 524278, 1048566, 2097142, 4194294, 8388598, 16777206, 33554422, 67108854, 134217718, 268435446, 536870902, 1073741814, 2147483638
Offset: 0

Views

Author

Vincenzo Librandi, Aug 18 2014

Keywords

Crossrefs

Sequences of the form 2^n-k: A000079 (k=0), A000225 (k=1), A000918 (k=2), A036563 (k=3), A028399 (k=4), A168616 (k=5), A131130 (k=6), A048490 (k=7), A159741 (k=8), A185346 (k=9), this sequence (k=10).

Programs

  • Magma
    [2^n-10: n in [0..40]];
    
  • Mathematica
    Table[2^n - 10, {n, 0, 35}] (* or *) CoefficientList[Series[(-9 + 19 x)/(1 - 3 x + 2 x^2), {x, 0, 35}], x]
    LinearRecurrence[{3,-2},{-9,-8},50] (* Harvey P. Dale, Jan 11 2024 *)
  • PARI
    vector(50, n, 2^(n-1)-10) \\ Derek Orr, Aug 18 2014

Formula

G.f.: (-9+19*x)/(1-3*x+2*x^2).
a(n) = 3*a(n-1) - 2*a(n-2).
a(n) = A000079(n) - 10.
From Elmo R. Oliveira, Dec 21 2023: (Start)
a(n) = 2*a(n-1) + 10 for n>0.
E.g.f.: exp(x)*(exp(x) - 10). (End)

A036982 a(n)=[ a*a(n-1)+b ]/p^r, where a=2.001, b=3.2, p=2 and p^r is the highest power of p dividing [ a*a(n-1)+b ].

Original entry on oeis.org

1, 5, 13, 29, 61, 125, 253, 509, 1021, 1023, 1025, 1027, 1029, 1031, 1033, 1035, 1037, 1039, 1041, 1043, 1045, 1047, 1049, 1051, 1053, 1055, 1057, 1059, 1061, 1063, 1065, 1067, 1069, 1071, 1073, 1075, 1077, 1079, 1081, 1083, 1085, 1087, 1089, 1091, 1093
Offset: 0

Views

Author

Keywords

Comments

A cyclic sequence. The period is 6767.
If an array is made of columns of -nacci sequences, fibo-, tribo- etc. all starting w. 1,1,2 etc, the nw to se diagonals can be extended by computation. The above minus the first digit is diagonal 4. See A159741 for details. [From Al Hakanson (hawkuu(AT)gmail.com), Apr 20 2009]

Crossrefs

Cf. A029580.

Extensions

More terms from James Sellers, Aug 08 2000

A172252 a(n) = 4*2^n - 9.

Original entry on oeis.org

-1, 7, 23, 55, 119, 247, 503, 1015, 2039, 4087, 8183, 16375, 32759, 65527, 131063, 262135, 524279, 1048567, 2097143, 4194295, 8388599, 16777207, 33554423, 67108855, 134217719, 268435447, 536870903, 1073741815, 2147483639, 4294967287, 8589934583, 17179869175, 34359738359
Offset: 1

Views

Author

Artur Jasinski, Jan 29 2010

Keywords

Crossrefs

Programs

  • Mathematica
    Table[4 2^n - 9, {n, 1, 100}]
    LinearRecurrence[{3,-2},{-1,7},30] (* Harvey P. Dale, May 27 2021 *)
  • PARI
    my(x='x+O('x^34)); Vec(x*(10*x-1)/((x-1)*(2*x-1))) \\ Elmo R. Oliveira, Jun 15 2025

Formula

a(n) = 2*a(n-1) + 9, a(1)= -1. - Vincenzo Librandi, Mar 20 2011
For n >= 3, a(n) = 8<+>(n+2), where operation <+> is defined in A206853. - Vladimir Shevelev, Feb 17 2012
From Elmo R. Oliveira, Jun 15 2025: (Start)
G.f.: x*(10*x-1)/((x-1)*(2*x-1)).
E.g.f.: 5 + exp(x)*(4*exp(x) - 9).
a(n) = A185346(n+2) = 4*A000225(n) - 5.
a(n) = A159741(n-1) - 1 for n > 1. (End)

Extensions

More terms from Elmo R. Oliveira, Jun 15 2025

A341419 a(0) = 1, a(1) = 1, a(2^(n-1)..2^n-1) = fwht(0..2^(n-2)). Here "fwht" is the fast Walsh-Hadamard transform with natural ordering and without multiplication of any factors.

Original entry on oeis.org

1, 1, 2, 0, 4, 2, 0, -2, 8, 6, 8, -2, 0, -2, -8, -2, 16, 14, 24, -2, 32, 14, -8, -18, 0, -2, -8, -2, -32, -18, -8, 14, 32, 30, 56, -2, 96, 46, -8, -50, 128, 94, 120, -34, -32, -50, -136, -18, 0, -2, -8, -2, -32, -18, -8, 14, -128, -98, -136, 30, -32, 14, 120, 46, 64, 62
Offset: 0

Views

Author

Thomas Scheuerle, Mar 24 2021

Keywords

Comments

This sequence is a rough integer-valued approximation to one of the nontrivial solutions to f(n) = a*fwht(f(n)).

Crossrefs

Programs

  • MATLAB
    function a = A341419(max_n)
    a(1) = 1;
    a(2) = 1;
        while length(a) < max_n
            w = fwht(a,[],'hadamard')*length(a);
            %w = myfwht(a); % own implementation for documentation purpose
            a = [a w];
        end
    end
    function w = myfwht(in)
        h = 1;
        while h < length(in)
            for i = 1:h*2:length(in)
                for j = i:i+h-1
                    x = in(j);
                    y = in(j+h);
                    in(j) = x+y;
                    in(j+h) = x-y;
                end
            end
            h = h*2;
        end
        w = in;
    end

Formula

a(2^n) = 2^n.
a(2^n + 1) = 2^n-2 for n > 0.
a(2^n + 2) = 8*(2^(n-2) - 1) = A159741(n-2) for n > 1.
a(2^n + 3) = -2 for n > 1.
a(2^n + 4) = 32*(2^(n-3) - 1) = A175165(n-3) for n > 2.
a(2^n + 5) = 2*(2^n - 9) for n > 2.
a(2^n + 6) = -8 for n > 2.
a(2^n + 7) = -2*(8 * 2^(n-3) - 7) for n > 2.
a(2^n + 8) = 64*(2^(n-3) - 2) for n > 3.
Previous Showing 11-16 of 16 results.