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.

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A076313 a(n) = floor(n/10) - (n mod 10).

Original entry on oeis.org

0, -1, -2, -3, -4, -5, -6, -7, -8, -9, 1, 0, -1, -2, -3, -4, -5, -6, -7, -8, 2, 1, 0, -1, -2, -3, -4, -5, -6, -7, 3, 2, 1, 0, -1, -2, -3, -4, -5, -6, 4, 3, 2, 1, 0, -1, -2, -3, -4, -5, 5, 4, 3, 2, 1, 0, -1, -2, -3, -4, 6, 5, 4, 3, 2, 1, 0, -1, -2, -3, 7, 6, 5, 4, 3, 2, 1, 0, -1, -2, 8, 7, 6, 5, 4
Offset: 0

Views

Author

Reinhard Zumkeller, Oct 06 2002

Keywords

Comments

For n<100 equal to the negated alternating digital sum of n (see A055017). - Hieronymus Fischer, Jun 17 2007

Crossrefs

Programs

  • Haskell
    a076313 = uncurry (-) . flip divMod 10 -- Reinhard Zumkeller, Jun 01 2013
  • Mathematica
    Table[Floor[n/10]-Mod[n,10],{n,0,100}] (* or *) LinearRecurrence[{1,0,0,0,0,0,0,0,0,1,-1},{0,-1,-2,-3,-4,-5,-6,-7,-8,-9,1},100] (* Harvey P. Dale, Nov 02 2022 *)
  • PARI
    a(n)=n\10-n%10 \\ Charles R Greathouse IV, Jan 30 2012
    

Formula

From Hieronymus Fischer, Jun 17 2007: (Start)
a(n) = 11*floor(n/10)-n.
a(n) = (n-11*(n mod 10))/10.
a(n) = 11*A002266(A004526(n))-n=11*A004526(A002266(n))-n.
a(n) = (n-11*A010879(n))/10.
a(n) = (n-11*A000035(n)-22*A010874(A004526(n)))/10.
a(n) = (n-11*A010874(n)-55*A000035(A002266(n)))/10.
G.f.: x*(-8*x^10+11*x^9-1)/((1-x^10)*(1-x)^2). (End)

A133875 n modulo 5 repeated 5 times.

Original entry on oeis.org

1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1
Offset: 0

Views

Author

Hieronymus Fischer, Oct 10 2007

Keywords

Comments

Periodic with length 5^2 = 25.

Crossrefs

Programs

  • Magma
    [(1 + Floor(n/5)) mod 5 : n in [0..50]]; // Wesley Ivan Hurt, Jun 06 2014
  • Maple
    A133875:=n->((1+floor(n/5)) mod 5); seq(A133875(n), n=0..100); # Wesley Ivan Hurt, Jun 06 2014
  • Mathematica
    Table[Mod[1 + Floor[n/5], 5], {n, 0, 100}] (* Wesley Ivan Hurt, Jun 06 2014 *)
    LinearRecurrence[{1,0,0,0,-1,1,0,0,0,-1,1,0,0,0,-1,1,0,0,0,-1,1},{1,1,1,1,1,2,2,2,2,2,3,3,3,3,3,4,4,4,4,4,0},120] (* Harvey P. Dale, Dec 14 2017 *)

Formula

a(n) = (1 + floor(n/5)) mod 5.
a(n) = A010874(A002266(n+5)).
a(n) = 1 + floor(n/5) - 5*floor((n+5)/25).
a(n) = (((n+5) mod 25) - (n mod 5)) / 5.
a(n) = ((n + 5 - (n mod 5)) / 5) mod 5.
a(n) = A010874((n + 5 - A010874(n))/5).
a(n) = binomial(n+5, n) mod 5 = binomial(n+5, 5) mod 5.
a(n) = +a(n-1) -a(n-5) +a(n-6) -a(n-10) +a(n-11) -a(n-15) +a(n-16) -a(n-20) +a(n-21). - R. J. Mathar, Sep 03 2011
G.f.: ( 1+2*x^5+3*x^10+4*x^15 ) / ( (1-x)*(x^20+x^15+x^10+x^5+1) ). - R. J. Mathar, Sep 03 2011

A010883 Simple periodic sequence: repeat 1,2,3,4.

Original entry on oeis.org

1, 2, 3, 4, 1, 2, 3, 4, 1, 2, 3, 4, 1, 2, 3, 4, 1, 2, 3, 4, 1, 2, 3, 4, 1, 2, 3, 4, 1, 2, 3, 4, 1, 2, 3, 4, 1, 2, 3, 4, 1, 2, 3, 4, 1, 2, 3, 4, 1, 2, 3, 4, 1, 2, 3, 4, 1, 2, 3, 4, 1, 2, 3, 4, 1, 2, 3, 4, 1, 2, 3, 4, 1, 2, 3, 4, 1, 2, 3, 4, 1
Offset: 0

Views

Author

Keywords

Comments

Partial sums are given by A130482(n) + n + 1. - Hieronymus Fischer, Jun 08 2007
1234/9999 = 0.123412341234... - Eric Desbiaux, Nov 03 2008

Crossrefs

Cf. A177037 (decimal expansion of (9+2*sqrt(39))/15). - Klaus Brockhaus, May 01 2010

Programs

Formula

a(n) = 1 + (n mod 4). - Paolo P. Lava, Nov 21 2006
From Hieronymus Fischer, Jun 08 2007: (Start)
a(n) = A010873(n) + 1.
Also a(n) = (1/2)*(5 - (-1)^n - 2*(-1)^((2*n - 1 + (-1)^n)/4)).
G.f.: g(x) = (4*x^3 + 3*x^2 + 2*x + 1)/(1 - x^4) = (4*x^5 - 5*x^4 + 1)/((1 - x^4)*(1-x)^2). (End)
a(n) = 5/2 - cos(Pi*n/2) - sin(Pi*n/2) - (-1)^n/2. - R. J. Mathar, Oct 08 2011

A099546 Odd part of n modulo 5.

Original entry on oeis.org

1, 1, 3, 1, 0, 3, 2, 1, 4, 0, 1, 3, 3, 2, 0, 1, 2, 4, 4, 0, 1, 1, 3, 3, 0, 3, 2, 2, 4, 0, 1, 1, 3, 2, 0, 4, 2, 4, 4, 0, 1, 1, 3, 1, 0, 3, 2, 3, 4, 0, 1, 3, 3, 2, 0, 2, 2, 4, 4, 0, 1, 1, 3, 1, 0, 3, 2, 2, 4, 0, 1, 4, 3, 2, 0, 4, 2, 4, 4, 0, 1, 1, 3, 1, 0, 3, 2, 1, 4, 0, 1, 3, 3, 2, 0, 3, 2, 4, 4, 0, 1, 1
Offset: 1

Views

Author

Ralf Stephan, Oct 23 2004

Keywords

Crossrefs

Programs

  • Mathematica
    a[n_] := Mod[n / 2^IntegerExponent[n, 2], 5]; Array[a, 100] (* Amiram Eldar, Aug 29 2024 *)
  • PARI
    a(n) = (n>>valuation(n, 2))%5 \\Charles R Greathouse IV, May 14 2014

Formula

a(n) = A010874(A000265(n)).
Asymptotic mean: Limit_{m->oo} (1/m) * Sum_{k=1..m} a(k) = 2. - Amiram Eldar, Aug 29 2024

A130488 a(n) = Sum_{k=0..n} (k mod 10) (Partial sums of A010879).

Original entry on oeis.org

0, 1, 3, 6, 10, 15, 21, 28, 36, 45, 45, 46, 48, 51, 55, 60, 66, 73, 81, 90, 90, 91, 93, 96, 100, 105, 111, 118, 126, 135, 135, 136, 138, 141, 145, 150, 156, 163, 171, 180, 180, 181, 183, 186, 190, 195, 201, 208, 216, 225, 225, 226, 228, 231, 235, 240, 246, 253
Offset: 0

Views

Author

Hieronymus Fischer, May 31 2007

Keywords

Comments

Let A be the Hessenberg n X n matrix defined by A[1,j] = j mod 10, A[i,i]:=1, A[i,i-1]=-1. Then, for n >= 1, a(n)=det(A). - Milan Janjic, Jan 24 2010

Crossrefs

Programs

  • GAP
    a:=[0,1,3,6,10,15,21,28,36,45,45];; for n in [12..61] do a[n]:=a[n-1]+a[n-10]-a[n-11]; od; a; # G. C. Greubel, Aug 31 2019
    
  • Magma
    I:=[0,1,3,6,10,15,21,28,36,45,45]; [n le 11 select I[n] else Self(n-1) + Self(n-10) - Self(n-11): n in [1..61]]; // G. C. Greubel, Aug 31 2019
    
  • Maple
    seq(coeff(series(x*(1-10*x^9+9*x^10)/((1-x^10)*(1-x)^3), x, n+1), x, n), n = 0..60); # G. C. Greubel, Aug 31 2019
  • Mathematica
    LinearRecurrence[{1,0,0,0,0,0,0,0,0,1,-1}, {0,1,3,6,10,15,21,28,36,45, 45}, 60] (* G. C. Greubel, Aug 31 2019 *)
  • PARI
    a(n) = sum(k=0, n, k % 10); \\ Michel Marcus, Apr 28 2018
    
  • Python
    def A130488(n):
        a, b = divmod(n,10)
        return 45*a+(b*(b+1)>>1) # Chai Wah Wu, Jul 27 2022
  • Sage
    def A130488_list(prec):
        P. = PowerSeriesRing(ZZ, prec)
        return P(x*(1-10*x^9+9*x^10)/((1-x^10)*(1-x)^3)).list()
    A130488_list(60) # G. C. Greubel, Aug 31 2019
    

Formula

a(n) = 45*floor(n/10) + A010879(n)*(A010879(n) + 1)/2.
G.f.: (Sum_{k=1..9} k*x^k)/((1-x^10)*(1-x)).
G.f.: x*(1 - 10*x^9 + 9*x^10)/((1-x^10)*(1-x)^3).

A156174 Period 5: repeat [1,-1,1,-1,0].

Original entry on oeis.org

1, -1, 1, -1, 0, 1, -1, 1, -1, 0, 1, -1, 1, -1, 0, 1, -1, 1, -1, 0, 1, -1, 1, -1, 0, 1, -1, 1, -1, 0, 1, -1, 1, -1, 0, 1, -1, 1, -1, 0, 1, -1, 1, -1, 0, 1, -1, 1, -1, 0, 1, -1, 1, -1, 0, 1, -1, 1, -1, 0, 1, -1, 1, -1, 0, 1, -1, 1, -1, 0, 1, -1, 1, -1, 0, 1, -1, 1, -1, 0, 1, -1, 1, -1, 0, 1, -1, 1, -1, 0, 1, -1, 1, -1, 0, 1, -1, 1, -1, 0, 1, -1, 1, -1, 0
Offset: 0

Views

Author

N. J. A. Sloane, Nov 06 2009

Keywords

Comments

C(n) := a(n+4) appears in the formula 2*exp(2*Pi*n*i/5) = (A(n) + B(n)*phi) + (C(n) + D(n)*phi)*sqrt(2 + phi)*i, with the golden section phi, i = sqrt(-1) and A(n) = A164116(n+5), B(n) = A080891(n) and D(n) = A010891(n+3) for n >= 0. See a comment on A164116(n+5). - Wolfdieter Lang, Feb 26 2014
With offset 1 this is a strong elliptic divisibility sequence t_n as given in [Kimberling, p. 16] where x = -1, y = 1, z = 1. - Michael Somos, Oct 17 2018

Examples

			G.f. = 1 - x + x^2 - x^3 + x^5 - x^6 + x^7 - x^8 + x^10 - x^11 + x^12 + ...
		

References

  • Arthur Gill, Linear Sequential Circuits, McGraw-Hill, 1966, Eq. (17-10).

Crossrefs

Cf. A010874, A011558 (this read mod 2), A099443, A198517.

Programs

Formula

G.f.: (1+x^2)/(1 + x + x^2 + x^3 + x^4).
Sum_{i=0..n} a(i) = A198517(n). - Bruno Berselli, Nov 02 2011
From Wesley Ivan Hurt, May 31 2015: (Start)
a(n) + a(n-1) + a(n-2) + a(n-3) + a(n-4) = 0 for n > 4.
a(n) = Sum_{i=0..3} A011558(n+2+i)*(-1)^i. (End)
Euler transform of length 5 sequence [-1, 1, 0, -1, 1]. - Michael Somos, Jun 17 2015
G.f.: (1-x)*(1-x^4)/((1-x^2)*(1-x^5)). - Michael Somos, Jun 17 2015
a(n) = -a(-2-n) = a(n+5) for all n in Z. - Michael Somos, Jun 17 2015
a(n) = (2/5) * (cos(4*(n-2)*Pi/5) + cos(2*n*Pi/5) + cos(4*n*Pi/5) - cos(2*(n-3)*Pi/5) - cos(4*(n-3)*Pi/5) - cos(2*(n-1)*Pi/5) - cos(4*(n-1)*Pi/5) - cos((2*n+1)*Pi/5)). - Wesley Ivan Hurt, Sep 26 2018
a(n) = (-1)^n * A099443(n). - Michael Somos, Oct 17 2018
a(5*n) = a(5*n + 2) = 1, a(5*n + 1) = a(5*n + 3) = -1, a(5*n + 4) = 0 for all n in Z. - Michael Somos, Nov 27 2019

A177154 Fractional part of the conversion from degrees Celsius to Fahrenheit.

Original entry on oeis.org

0, 8, 6, 4, 2, 0, 8, 6, 4, 2, 0, 8, 6, 4, 2, 0, 8, 6, 4, 2, 0, 8, 6, 4, 2, 0, 8, 6, 4, 2, 0, 8, 6, 4, 2, 0, 8, 6, 4, 2, 0, 8, 6, 4, 2, 0, 8, 6, 4, 2, 0, 8, 6, 4, 2, 0, 8, 6, 4, 2, 0, 8, 6, 4, 2, 0, 8, 6, 4, 2, 0, 8, 6, 4, 2, 0, 8, 6, 4, 2, 0, 8, 6, 4, 2, 0, 8, 6, 4, 2, 0, 8, 6, 4, 2, 0, 8, 6, 4, 2, 0, 8, 6, 4, 2
Offset: 0

Views

Author

Reinhard Zumkeller, May 03 2010

Keywords

Comments

From Klaus Brockhaus, May 06 2010: (Start)
Periodic sequence: Repeat 0, 8, 6, 4, 2.
Decimal expansion of 8642/99999. (End)

Crossrefs

Programs

  • Mathematica
    PadRight[{}, 100, {0, 8, 6, 4, 2}] (* Paolo Xausa, Jan 29 2024 *)

Formula

(A085259(n) + a(n)/10 - 32) * 5 / 9 = n;
A029925(n) - A085259(n) = floor(a(n)/5);
G.f.: 2*x*(4+3*x+2*x^2+x^3)/(1-x^5). - Klaus Brockhaus, May 06 2010

A277543 a(n) = n/5^m mod 5, where 5^m is the greatest power of 5 that divides n.

Original entry on oeis.org

1, 2, 3, 4, 1, 1, 2, 3, 4, 2, 1, 2, 3, 4, 3, 1, 2, 3, 4, 4, 1, 2, 3, 4, 1, 1, 2, 3, 4, 1, 1, 2, 3, 4, 2, 1, 2, 3, 4, 3, 1, 2, 3, 4, 4, 1, 2, 3, 4, 2, 1, 2, 3, 4, 1, 1, 2, 3, 4, 2, 1, 2, 3, 4, 3, 1, 2, 3, 4, 4, 1, 2, 3, 4, 3, 1, 2, 3, 4, 1, 1, 2, 3, 4, 2, 1
Offset: 1

Views

Author

Clark Kimberling, Oct 19 2016

Keywords

Comments

a(n) is the rightmost nonzero digit in the base 5 expansion of n (A007091).

Examples

			a(20) = (20/5 mod 5) = 4.
		

Crossrefs

Cf. A277550, A277551, A277555, A277548 (positions of 1, 2, 3 and 4 in this sequence).

Programs

  • Mathematica
    Table[Mod[n/5^IntegerExponent[n, 5], 5], {n, 1, 160}]
  • PARI
    a(n) = n/5^valuation(n, 5) % 5; \\ Michel Marcus, Oct 20 2016

Formula

a(n) = A132739(n) mod 5 = A010874(A132739(n)). - Michel Marcus, Oct 20 2016

A010887 Simple periodic sequence: repeat 1,2,3,4,5,6,7,8.

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 8, 1, 2, 3, 4, 5, 6, 7, 8, 1, 2, 3, 4, 5, 6, 7, 8, 1, 2, 3, 4, 5, 6, 7, 8, 1, 2, 3, 4, 5, 6, 7, 8, 1, 2, 3, 4, 5, 6, 7, 8, 1, 2, 3, 4, 5, 6, 7, 8, 1, 2, 3, 4, 5, 6, 7, 8, 1, 2, 3, 4, 5, 6, 7, 8, 1, 2, 3, 4, 5, 6, 7, 8, 1
Offset: 0

Views

Author

Keywords

Comments

Partial sums are given by A130486(n)+n+1. - Hieronymus Fischer, Jun 08 2007
1371742/11111111 = 0.123456781234567812345678... - Eric Desbiaux, Nov 03 2008

Crossrefs

Cf. A177034 (decimal expansion of (9280+3*sqrt(13493990))/14165). - Klaus Brockhaus, May 01 2010

Programs

  • Haskell
    a010887 = (+ 1) . flip mod 8
    a010887_list = cycle [1..8]
    -- Reinhard Zumkeller, Nov 09 2014, Mar 04 2014
    
  • Mathematica
    PadRight[{},90,Range[8]] (* Harvey P. Dale, May 10 2022 *)
  • Python
    def A010887(n): return 1 + (n & 7) # Chai Wah Wu, May 25 2022

Formula

a(n) = 1 + (n mod 8) - Paolo P. Lava, Nov 21 2006
From Hieronymus Fischer, Jun 08 2007: (Start)
a(n) = (1/2)*(9 - (-1)^n - 2*(-1)^(b/4) - 4*(-1)^((b - 2 + 2*(-1)^(b/4))/8)) where b = 2n - 1 + (-1)^n.
Also a(n) = A010877(n) + 1.
G.f.: g(x) = (1/(1-x^8))*Sum_{k=0..7} (k+1)*x^k.
Also: g(x) = (8x^9 - 9x^8 + 1)/((1-x^8)*(1-x)^2). (End)

A060154 Table T(n,k) by antidiagonals of n^k mod k [n,k >= 1].

Original entry on oeis.org

0, 1, 0, 1, 0, 0, 1, 2, 1, 0, 1, 0, 0, 0, 0, 1, 2, 1, 1, 1, 0, 1, 4, 3, 0, 2, 0, 0, 1, 2, 3, 4, 1, 0, 1, 0, 1, 0, 3, 4, 0, 0, 1, 0, 0, 1, 8, 1, 4, 1, 1, 1, 2, 1, 0, 1, 4, 0, 0, 5, 0, 2, 0, 0, 0, 0, 1, 2, 9, 1, 1, 6, 1, 3, 1, 1, 1, 0, 1, 4, 3, 6, 8, 0, 0, 4, 4, 0, 2, 0, 0, 1, 2, 9, 4, 5, 0, 1, 1, 3, 0, 1, 0, 1, 0
Offset: 1

Views

Author

Henry Bottomley, Mar 12 2001

Keywords

Examples

			T(5,3) = 5^3 mod 3 = 125 mod 3 = 2.
Rows start:
  0, 1, 1, 1, 1, ...
  0, 0, 2, 0, 2, ...
  0, 1, 0, 1, 3, ...
  0, 0, 1, 0, 4, ...
  0, 1, 2, 1, 0, ...
		

Crossrefs

Rows include A057427, A015910, A056969.
Columns include A000004, A000035 (several times), A010872, A010874, A010876, A021559 and other periodic sequences.
Diagonals include A000004 and A057427.
Cf. A114448.

Formula

T(n, k) = A051129(n, k)-n*A060155(n, k).
Previous Showing 21-30 of 57 results. Next