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.

A180363 a(n) = Lucas(prime(n)).

Original entry on oeis.org

3, 4, 11, 29, 199, 521, 3571, 9349, 64079, 1149851, 3010349, 54018521, 370248451, 969323029, 6643838879, 119218851371, 2139295485799, 5600748293801, 100501350283429, 688846502588399, 1803423556807921, 32361122672259149, 221806434537978679
Offset: 1

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Author

Jonathan Vos Post, Aug 31 2010

Keywords

Comments

This is to A030426, Fibonacci(prime(n)), as A000032 (Lucas numbers beginning at 2) is to A000045.

Examples

			a(1) = 3 because the 1st prime is 2, and the 2nd Lucas number is A000032(2) = 3.
a(2) = 4 because the 2nd prime is 3, and the 3rd Lucas number is A000032(3) = 4.
a(3) = 11 because the 3rd prime is 5, and the 5th Lucas number is A000032(5) = 11.
		

Crossrefs

Programs

  • Magma
    [Lucas(NthPrime(n)): n in [1..30]]; // Vincenzo Librandi, Dec 01 2015
    
  • Maple
    A180363 := proc(n) A000032(ithprime(n)) ; end proc: seq(A180363(n),n=1..30) ; # R. J. Mathar, Sep 01 2010
    # second Maple program:
    a:= n-> (<<1|1>, <1|0>>^ithprime(n). <<2, -1>>)[1, 1]:
    seq(a(n), n=1..50);  # Alois P. Heinz, Jan 03 2022
  • Mathematica
    LucasL[Prime[Range[30]]] (* Vincenzo Librandi, Dec 01 2015 *)
  • Python
    from sympy import lucas, prime
    def a(n): return lucas(prime(n))
    print([a(n) for n in range(1, 24)]) # Michael S. Branicky, Dec 30 2021

Formula

a(n) = A000032(A000040(n)) = Lucas(prime(n)).
a(n) = A032170(A000040(n)) / A064723(n-1) - 1 for n>1. - Flávio V. Fernandes, Dec 30 2021

Extensions

Entries checked by R. J. Mathar, Sep 01 2010
Edited by N. J. A. Sloane, Nov 28 2011

A014981 a(n) = c(prime(n))/prime(n), where c = Perrin sequence A001608 (starting 0,2,3,...) and prime(n) is the n-th prime.

Original entry on oeis.org

1, 1, 1, 1, 2, 3, 7, 11, 28, 120, 197, 892, 2479, 4148, 11687, 56010, 271913, 461529, 2270882, 6599404, 11263855, 56250108, 164879269, 830987861, 7231032935, 21386730355, 36802336319, 109099442316, 187943217386
Offset: 1

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Author

Keywords

Crossrefs

See A001608, the main entry for the Perrin sequence.

Programs

  • PARI
    c(n) = polsym(x^3-x-1,n)[n+1]; \\ A001608
    a(n) = my(p=prime(n)); c(p)/p; \\ Michel Marcus, Mar 03 2022

A242926 a(n) = denominator of B(0,n), where B(n,n) = 0, B(n-1,n) = 1/n and otherwise B(m,n) = B(m-1,n+1) - B(m-1,n).

Original entry on oeis.org

1, 1, 1, 2, 1, 6, 1, 4, 3, 5, 1, 4, 1, 7, 15, 8, 1, 18, 1, 10, 21, 11, 1, 24, 5, 13, 9, 14, 1, 30, 1, 16, 11, 17, 35, 12, 1, 19, 39, 20, 1, 42, 1, 22, 9, 23, 1, 48, 7, 25, 17, 26, 1, 54, 55, 28, 19, 29, 1, 20, 1
Offset: 0

Views

Author

Paul Curtz, May 26 2014

Keywords

Comments

The numerators are A189731(n).
B(0,n) = 0, 1, 1, 3/2, 2, 17/6, 4, 23/4, 25/3, 61/5, 18, 107/4, 40, 421/7, ...
is a super autosequence as defined in A242563.
The positive integers in B(0,n) give A064723(n). Corresponding rank: A006093(n+1). B(0,n) is linked to the primes A000040.
Divisor of B(0,n), n > 0: 1, 1, 1, 2, 2, 4, 5, ... = A172128(n+1).
Common (LCM) denominators for the antidiagonals: 1, 1, 1, 2, 2, 6, 6, 12, 12, ... = A139550(n+1)?.
1 = 1
1/2 + 3/2 = 2
1/3 + 5/6 + 17/6 = 4
1/4 + 7/12 + 7/4 + 23/4 = 25/3
etc.
The positive terms of the first bisection are the sum of the corresponding antidiagonal terms upon the 0's.
0 followed by A001610(n), i.e., 0, 0, 2, 3, 6, 10, 17, ... is an autosequence of the second kind.

Crossrefs

Programs

  • Mathematica
    Table[Denominator[(LucasL[n+1]-1)/(n+1)], {n, 0, 100}] (* Artur Jasinski, Nov 06 2022 *)

Formula

a(2n+1) = A175386(n).
a(n) = denominator(A001610(n)/(n+1)). [edited by Michel Marcus, Nov 14 2022]
a(n) = denominator((A000204(n+1) - 1)/(n+1)). - Artur Jasinski, Nov 06 2022

Extensions

a(24)-a(60) from Jean-François Alcover, May 26 2014

A213327 Analog of Fermat quotients: a(n) = (round((phi_2)^p)-2)/p, where phi_2 is silver ratio 1+sqrt(2) and p = prime(n).

Original entry on oeis.org

2, 4, 16, 68, 1476, 7280, 189120, 986244, 27676612, 4346071600, 23696518916, 3930960079760, 120508933265760, 669708812842692, 20814182249890948, 3654563002853231440, 650000099752136709444, 3664265812073801505200, 660535426260570501876228
Offset: 1

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Author

Keywords

Comments

For similar sequence for base 2, see A007663, for a similar sequence for golden ratio, see A064723.

Crossrefs

A213328 Analog of Fermat quotients: a(n) = (round((phi_3)^p)-3)/p, where phi_3 = (3+sqrt(13))/2 and p = prime(n).

Original entry on oeis.org

4, 11, 78, 612, 46374, 428040, 38948910, 380144556, 37367223558, 38467601033550, 392545092308724, 426897839167539480, 45841425452161683630, 476794964068892779068, 51906117696097060014342, 59746844088106673671809870, 69664778857791165966384195366
Offset: 1

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Author

Keywords

Comments

For similar sequence for base 2, see A007663. For similar sequences for golden ratio and silver ratio, see A064723 and A213327. Note that phi_3 is called "bronze ratio".

Crossrefs

A096540 Quotients T(p,k)/p, where T(p,k) is the sub-triangle defined in A096539 of the triangle of coefficients of Lucas polynomials (cf. A034807).

Original entry on oeis.org

1, 1, 1, 1, 1, 2, 1, 1, 4, 7, 5, 1, 1, 5, 12, 14, 7, 1, 1, 7, 26, 55, 66, 42, 12, 1, 1, 8, 35, 91, 143, 132, 66, 15, 1, 1, 10, 57, 204, 476, 728, 715, 429, 143, 22, 1, 1, 13, 100, 506, 1771, 4389, 7752, 9690, 8398, 4862, 1768, 364, 35, 1, 1, 14, 117, 650, 2530, 7084, 14421
Offset: 1

Views

Author

Lekraj Beedassy, Jun 24 2004

Keywords

Crossrefs

Row sums are in A064723. - Klaus Brockhaus, May 29 2009

Programs

  • PARI
    T(n,k)=if(k<0 || 2*k>n,0,binomial(n-k,k)+binomial(n-k-1,k-1)+(n==0 && k==0)) \\from A034807
    forprime(p=2,31, for(k=1,p\2,print1(T(p,k)/p,",")))

Extensions

Edited and extended by Klaus Brockhaus, Jun 27 2004
Showing 1-6 of 6 results.