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 31-36 of 36 results.

A010886 Period 7: repeat [1, 2, 3, 4, 5, 6, 7].

Original entry on oeis.org

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

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Author

Keywords

Comments

Partial sums are given by A130485(n)+n+1. - Hieronymus Fischer, Jun 08 2007
Decimal expansion of 1234567/9999999 = 0.123456712345671234567... - Eric Desbiaux, Nov 03 2008

Crossrefs

Cf. A177160 (decimal expansion of (4502+sqrt(29964677))/6961).

Programs

Formula

a(n) = 1 + (n mod 7). - Paolo P. Lava, Nov 21 2006
a(n) = A010876(n) + 1. G.f.: (Sum_{k=0..6} (k+1)*x^k)/(1-x^7). Also (7*x^8-8*x^7+1)/((1-x^7)*(1-x)^2). - Hieronymus Fischer, Jun 08 2007
From Wesley Ivan Hurt, Jul 18 2016: (Start)
a(n) = a(n-7) for n>6.
a(n) = 1 - 6*floor(n/7) + Sum_{k=1..6} floor((n + k)/7). (End)

A109753 n^3 mod 8; the periodic sequence {0,1,0,3,0,5,0,7}.

Original entry on oeis.org

0, 1, 0, 3, 0, 5, 0, 7, 0, 1, 0, 3, 0, 5, 0, 7, 0, 1, 0, 3, 0, 5, 0, 7, 0, 1, 0, 3, 0, 5, 0, 7, 0, 1, 0, 3, 0, 5, 0, 7, 0, 1, 0, 3, 0, 5, 0, 7, 0, 1, 0, 3, 0, 5, 0, 7, 0, 1, 0, 3, 0, 5, 0, 7, 0, 1, 0, 3, 0, 5, 0, 7, 0, 1, 0, 3, 0, 5, 0, 7, 0, 1, 0, 3, 0, 5, 0, 7, 0, 1, 0, 3, 0, 5, 0, 7, 0, 1, 0, 3, 0, 5, 0, 7, 0
Offset: 0

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Author

Bruce Corrigan (scentman(AT)myfamily.com), Aug 11 2005

Keywords

Crossrefs

Cf. n mod 8 = A010877; n^2 mod 8 = A070432.

Programs

Formula

G.f. = (x+3x^3+5x^5+7x^7)/(1-x^8)

A165242 The larger member of the n-th twin prime pair, modulo 8.

Original entry on oeis.org

5, 7, 5, 3, 7, 3, 5, 1, 7, 5, 3, 7, 5, 1, 7, 5, 1, 7, 3, 1, 5, 5, 1, 7, 3, 3, 1, 3, 3, 5, 3, 7, 5, 3, 3, 5, 1, 3, 7, 5, 1, 7, 7, 3, 7, 1, 5, 5, 3, 1, 1, 5, 5, 3, 3, 5, 1, 7, 5, 7, 7, 5, 3, 1, 1, 3, 7, 7, 5, 7, 5, 7, 7, 1, 3, 1, 1, 3, 7, 3, 3, 1, 1, 1, 5, 3, 5, 3, 1, 5, 7, 7, 5, 1, 5, 7, 7, 1, 1, 7, 5, 7, 3, 3, 5
Offset: 1

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Author

Jonathan Vos Post, Sep 09 2009

Keywords

Comments

Related to the rank of some elliptic curves by the conjecture on page 2 of [Hatley]:
Let E_p be the elliptic curve defined by y^2 = x(x-p)(x-2) where p and p-2 are twin primes.
Then Rank(E_p) = 0 if p == 7 (mod 8), 1 if p == 3,5 (mod 8), 2 if p == 1 (mod 8).

References

  • Joseph H. Silverman, The Arithmetic of Elliptic Curves, Springer-Verlag, 1986.

Crossrefs

Programs

  • Maple
    A006512 := proc(n) if n = 1 then 5; else for a from procname(n-1)+2 by 2 do if isprime(a) and isprime(a-2) then RETURN(a) ; fi; od: fi; end:
    A165242 := proc(n) A006512(n) mod 8 ; end: seq(A165242(n),n=1..120) ; # R. J. Mathar, Sep 16 2009
  • Mathematica
    Mod[#,8]&/@(Select[Partition[Prime[Range[800]],2,1],#[[2]]-#[[1]]==2&][[All,2]]) (* Harvey P. Dale, Sep 26 2016 *)

Formula

a(n) = A010877(A006512(n)).

Extensions

Redefined for the larger member of twin primes by R. J. Mathar, Sep 16 2009

A277546 a(n) = n/8^m mod 8, where 8^m is the greatest power of 8 that divides n.

Original entry on oeis.org

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

Views

Author

Clark Kimberling, Oct 19 2016

Keywords

Comments

a(n) is the rightmost nonzero digit in the base 8 expansion of n.

Examples

			a(11) = (11/8 mod 8) = 3.
		

Crossrefs

Cf. A010877.

Programs

  • Mathematica
    Table[Mod[n/8^IntegerExponent[n, 8], 8], {n, 1, 160}]
    m8[n_]:=Module[{idn=IntegerDigits[n,8]},While[idn[[-1]]==0,idn = Most[ idn]];idn[[-1]]]; Array[m8,90] (* Harvey P. Dale, Apr 02 2017 *)
  • PARI
    a(n) = n/8^valuation(n, 8) % 8; \\ Michel Marcus, Oct 20 2016

A290108 a(n) = A268819(n) mod 8.

Original entry on oeis.org

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

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Author

Antti Karttunen, Sep 11 2017

Keywords

Crossrefs

Programs

Formula

a(n) = A010877(A268819(n)) = A268819(n) mod 8.

A126048 Exponents p of the Mersenne primes 2^p - 1 (see A000043) read mod 8.

Original entry on oeis.org

2, 3, 5, 7, 5, 1, 3, 7, 5, 1, 3, 7, 1, 7, 7, 3, 1, 1, 5, 7, 1, 5, 5, 1, 5, 1, 1, 3, 7, 1, 3, 7, 1, 3, 5, 5, 1, 1, 5, 3, 7, 7, 1, 1, 3, 1, 1, 1
Offset: 1

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Author

Artur Jasinski, Dec 17 2006

Keywords

Crossrefs

Programs

  • Mathematica
    Mod[MersennePrimeExponent[Range[47]],8] (* Harvey P. Dale, Apr 18 2019 *)

Formula

a(n) = A010877(A000043(n)). - Ivan Panchenko, Apr 07 2018

Extensions

a(45)-a(46) from Ivan Panchenko, Apr 07 2018
a(47) from Ivan Panchenko, Apr 09 2018
a(48) from Amiram Eldar, Oct 14 2024
Previous Showing 31-36 of 36 results.