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 1-6 of 6 results.

A130910 Sum {0<=k<=n, k mod 16} (Partial sums of A130909).

Original entry on oeis.org

0, 1, 3, 6, 10, 15, 21, 28, 36, 45, 55, 66, 78, 91, 105, 120, 120, 121, 123, 126, 130, 135, 141, 148, 156, 165, 175, 186, 198, 211, 225, 240, 240, 241, 243, 246, 250, 255, 261, 268, 276, 285, 295, 306, 318, 331, 345, 360, 360, 361, 363, 366, 370, 375, 381, 388
Offset: 0

Views

Author

Hieronymus Fischer, Jun 11 2007

Keywords

Crossrefs

Programs

  • Mathematica
    Accumulate[Mod[Range[0,60],16]] (* Harvey P. Dale, May 30 2020 *)

Formula

a(n)=120*floor(n/16)+A130909(n)*(A130909(n)+1)/2. - G.f.: g(x)=(sum{1<=k<16, k*x^k})/((1-x^16)(1-x)). Also: g(x)=x(15x^16-16x^15+1)/((1-x^16)(1-x)^3).
a(n) = +a(n-1) +a(n-16) -a(n-17). G.f. ( x*(1 +2*x +3*x^2 +4*x^3 +5*x^4 +6*x^5 +7*x^6 +8*x^7 +9*x^8 +10*x^9 +11*x^10 +12*x^11 +13*x^12 +14*x^13 +15*x^14) ) / ( (1+x) *(1+x^2) *(1+x^4) *(1+x^8) *(x-1)^2 ). - R. J. Mathar, Nov 05 2011

A010877 a(n) = n mod 8.

Original entry on oeis.org

0, 1, 2, 3, 4, 5, 6, 7, 0, 1, 2, 3, 4, 5, 6, 7, 0, 1, 2, 3, 4, 5, 6, 7, 0, 1, 2, 3, 4, 5, 6, 7, 0, 1, 2, 3, 4, 5, 6, 7, 0, 1, 2, 3, 4, 5, 6, 7, 0, 1, 2, 3, 4, 5, 6, 7, 0, 1, 2, 3, 4, 5, 6, 7, 0, 1, 2, 3, 4, 5, 6, 7, 0, 1, 2, 3, 4, 5, 6, 7, 0
Offset: 0

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Author

Keywords

Comments

The rightmost digit in the base-8 representation of n. Also, the equivalent value of the three rightmost digits in the base-2 representation of n. - Hieronymus Fischer, Jun 12 2007

Crossrefs

Partial sums: A130486. Other related sequences A130481, A130482, A130483, A130484, A130485.

Programs

Formula

Complex representation: a(n) = (1/8)*(1-r^n)*Sum_{k=1..7} k*Product_{m=1..7, m<>k} (1 - r^(n-m)) where r = exp(Pi/4*i) = (1+i)*sqrt(2)/2 and i=sqrt(-1).
Trigonometric representation: a(n) = 256*(sin(n*Pi/8))^2*Sum_{k=1..7} k*Product_{m=1..7, m<>k} (sin((n-m)*Pi/8))^2.
G.f.: g(x) = (Sum_{k=1..7}, k*x^k)/(1-x^8).
Also: g(x) = x(7x^8-8x^7+1)/((1-x^8)(1-x)^2). - Hieronymus Fischer, May 31 2007
a(n) = n mod 2 + 2*(floor(n/2) mod 4) = A000035(n) + 2*A010873(A004526(n)).
a(n) = n mod 4 + 4*(floor(n/4) mod 2) = A010873(n) + 4*A000035(A002265(n)).
a(n) = n mod 2 + 2*(floor(n/2) mod 2) + 4*(floor(n/4) mod 2) = A000035(n) + 2*A000035(A004526(n)) + 4*A000035(A002265(n)). - Hieronymus Fischer, Jun 12 2007
a(n) = (1/2)*(7 - (-1)^n - 2*(-1)^(b/4) - 4*(-1)^((b - 2 + 2*(-1)^(b/4))/8)) where b = 2n - 1 + (-1)^n. - Hieronymus Fischer, Jun 12 2007
General formula for period 2^k: a(n) = (1/2)*(2^k - 1 - Sum_{j=0..k-1} 2^j*(-1)^p(j,n)) where p(j,n) is defined recursively by p(0,n)=n, p(j,n) = (1/4)*(2*p(j-1,n) - 1 + (-1)^p(j-1,n)). - Hieronymus Fischer, Jun 14 2007
a(n) = floor(1234567/99999999*10^(n+1)) mod 10. - Hieronymus Fischer, Jan 03 2013
a(n) = floor(48913/2396745*8^(n+1)) mod 8. - Hieronymus Fischer, Jan 04 2013

Extensions

Formula section re-edited for better readability by Hieronymus Fischer

A070370 a(n) = 5^n mod 16.

Original entry on oeis.org

1, 5, 9, 13, 1, 5, 9, 13, 1, 5, 9, 13, 1, 5, 9, 13, 1, 5, 9, 13, 1, 5, 9, 13, 1, 5, 9, 13, 1, 5, 9, 13, 1, 5, 9, 13, 1, 5, 9, 13, 1, 5, 9, 13, 1, 5, 9, 13, 1, 5, 9, 13, 1, 5, 9, 13, 1, 5, 9, 13, 1, 5, 9, 13, 1, 5, 9, 13, 1, 5, 9, 13, 1, 5, 9, 13, 1, 5, 9, 13, 1, 5, 9, 13, 1, 5, 9, 13, 1, 5, 9, 13, 1
Offset: 0

Views

Author

N. J. A. Sloane, May 12 2002

Keywords

Comments

Period 4: repeat [1, 5, 9, 13].

Crossrefs

Programs

Formula

From R. J. Mathar, Apr 20 2010: (Start)
a(n) = a(n-4) for n>3.
G.f.: ( 1+5*x+9*x^2+13*x^3 ) / ( (1-x)*(1+x)*(1+x^2) ). (End)
a(n) = 7-2*((1+I)*(-I)^n+(1-I)*I^n+(-1)^n). - Bruno Berselli, Feb 07 2011
E.g.f.: 5*cosh(x) + 9*sinh(x) - 4*cos(x) - 4*sin(x). - G. C. Greubel, Mar 05 2016
a(n) = A130909(A000351(n)). - Michel Marcus, Jul 06 2016

A070439 a(n) = n^2 mod 16.

Original entry on oeis.org

0, 1, 4, 9, 0, 9, 4, 1, 0, 1, 4, 9, 0, 9, 4, 1, 0, 1, 4, 9, 0, 9, 4, 1, 0, 1, 4, 9, 0, 9, 4, 1, 0, 1, 4, 9, 0, 9, 4, 1, 0, 1, 4, 9, 0, 9, 4, 1, 0, 1, 4, 9, 0, 9, 4, 1, 0, 1, 4, 9, 0, 9, 4, 1, 0, 1, 4, 9, 0, 9, 4, 1, 0, 1, 4, 9, 0, 9, 4, 1, 0, 1, 4, 9, 0, 9, 4, 1, 0, 1, 4, 9, 0, 9, 4, 1, 0, 1, 4, 9, 0
Offset: 0

Views

Author

N. J. A. Sloane, May 12 2002

Keywords

Crossrefs

Programs

Formula

G.f.: -x*(1+4*x+9*x^2+9*x^4+4*x^5+x^6) / ( (x-1)*(1+x)*(x^2+1)*(x^4+1) ). - R. J. Mathar, Jul 27 2015
a(n) = a(n-8). - G. C. Greubel, Mar 24 2016
a(n) = A130909(n^2). - Michel Marcus, Mar 24 2016

A126056 Exponents p of the Mersenne primes 2^p - 1 (see A000043) read mod 16.

Original entry on oeis.org

2, 3, 5, 7, 13, 1, 3, 15, 13, 9, 11, 15, 9, 15, 15, 11, 9, 1, 13, 7, 9, 5, 13, 1, 5, 9, 1, 3, 7, 1, 11, 7, 9, 11, 13, 13, 1, 1, 5, 11, 7, 7, 9, 1, 11, 9, 1, 9
Offset: 1

Views

Author

Artur Jasinski, Dec 17 2006

Keywords

Crossrefs

Programs

  • Mathematica
    Mod[MersennePrimeExponent[Range[48]], 16] (* Amiram Eldar, Oct 15 2024 *)

Formula

a(n) = A130909(A000043(n)). - Michel Marcus, Apr 07 2018

Extensions

a(45)-a(47) from Ivan Panchenko, Apr 08 2018
a(48) from Amiram Eldar, Oct 15 2024

A167166 a(n) = n^7 mod 16.

Original entry on oeis.org

0, 1, 0, 11, 0, 13, 0, 7, 0, 9, 0, 3, 0, 5, 0, 15, 0, 1, 0, 11, 0, 13, 0, 7, 0, 9, 0, 3, 0, 5, 0, 15, 0, 1, 0, 11, 0, 13, 0, 7, 0, 9, 0, 3, 0, 5, 0, 15, 0, 1, 0, 11, 0, 13, 0, 7, 0, 9, 0, 3, 0, 5, 0, 15, 0, 1, 0, 11, 0, 13, 0, 7, 0, 9, 0, 3, 0, 5, 0, 15, 0, 1, 0, 11, 0, 13, 0, 7, 0, 9, 0, 3, 0
Offset: 0

Views

Author

Zerinvary Lajos, Oct 29 2009

Keywords

Comments

Equivalently: n^(4*m+7) mod 16. - G. C. Greubel, Jun 04 2016

Programs

  • Mathematica
    Table[Mod[n^7, 16], {n, 0, 10}] (* G. C. Greubel, Jun 04 2016 *)
    PowerMod[Range[0,100],7,16] (* or *) PadRight[{},100,{0,1,0,11,0,13,0,7,0,9,0,3,0,5,0,15}] (* Harvey P. Dale, Jul 29 2018 *)
  • PARI
    a(n)=n^7%16 \\ Charles R Greathouse IV, Apr 06 2016
  • Sage
    [power_mod(n,7,16)for n in range(0, 93)] #
    

Formula

From R. J. Mathar, Sep 30 2013: (Start)
a(n) = a(n-16).
G.f. -x*(1 +11*x^2 +13*x^4 +7*x^6 +9*x^8 +3*x^10 +5*x^12 +15*x^14) / ( (x-1)*(1+x)*(1+x^2)*(1+x^4)*(1+x^8) ). (End)
a(n) = A130909(A001015(n)). - Michel Marcus, Jun 04 2016
Showing 1-6 of 6 results.