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 1-3 of 3 results.

A324907 a(n) = A007895(A113175(n)).

Original entry on oeis.org

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

Views

Author

Antti Karttunen, Apr 14 2019

Keywords

Crossrefs

Programs

  • PARI
    A113175(n) = { my(f = factor(n)); for(i=1, #f~, f[i, 1] = fibonacci(f[i, 1])); factorback(f); };
    A007895(n) = { my(s=0); while(n>0, s++; n -= fibonacci(1+A072649(n))); (s); }
    A072649(n) = { my(m); if(n<1, 0, m=0; until(fibonacci(m)>n, m++); m-2); }; \\ From A072649
    A324907(n) = A007895(A113175(n));

Formula

a(n) = A007895(A113175(n)).
a(2n) = a(n).

A328845 The first Fibonacci based variant of arithmetic derivative: a(p) = A000045(p) for prime p, a(u*v) = a(u)*v + u*a(v), with a(0) = a(1) = 0.

Original entry on oeis.org

0, 0, 1, 2, 4, 5, 7, 13, 12, 12, 15, 89, 20, 233, 33, 25, 32, 1597, 33, 4181, 40, 53, 189, 28657, 52, 50, 479, 54, 80, 514229, 65, 1346269, 80, 289, 3211, 100, 84, 24157817, 8381, 725, 100, 165580141, 127, 433494437, 400, 105, 57337, 2971215073, 128, 182, 125, 4825, 984, 53316291173, 135, 500, 188, 12581, 1028487, 956722026041, 160
Offset: 0

Views

Author

Antti Karttunen, Oct 28 2019

Keywords

Crossrefs

Cf. A374046 (indices of even terms), A374047 (of odd terms), A374122 (of multiples of 3), A374202 (2-adic valuation), A374203 (3-adic valuation), A374205 (5-adic valuation), A374125 [a(n) mod 360].
Cf. A374106 [gcd(a(n), A113177(n))], A374035 [gcd(a(n), A328846(n))], A374116 [gcd(a(n), A328768(n))].
For variants of the same formula, see A003415, A258851, A328768, A328769, A328846, A371192.

Programs

  • Mathematica
    A328845[n_] := If[n <= 1, 0, n*Total[MapApply[#2*Fibonacci[#]/# &, FactorInteger[n]]]];
    Array[A328845, 100, 0] (* Paolo Xausa, Dec 16 2024 *)
  • PARI
    A328845(n) = if(n<=1, 0, my(f=factor(n)); n*sum(i=1, #f~, f[i, 2]*fibonacci(f[i,1])/f[i, 1]));

Formula

a(n) = n * Sum e_j * A000045(p_j)/p_j for n = Product p_j^e_j.
a(A000040(n)) = A030426(n).
A007895(a(n)) = A328847(n).

A113176 Product_{p|n} F(p), where F(p) is the p-th Fibonacci number and where the product is over the distinct prime divisors of n.

Original entry on oeis.org

1, 1, 2, 1, 5, 2, 13, 1, 2, 5, 89, 2, 233, 13, 10, 1, 1597, 2, 4181, 5, 26, 89, 28657, 2, 5, 233, 2, 13, 514229, 10, 1346269, 1, 178, 1597, 65, 2, 24157817, 4181, 466, 5, 165580141, 26, 433494437, 89, 10, 28657, 2971215073, 2, 13, 5, 3194, 233
Offset: 1

Views

Author

Leroy Quet, Oct 16 2005

Keywords

Examples

			63 = 3^2 * 7^1. So a(63) = F(3) * F(7) = 2 * 13 = 26.
		

Crossrefs

Programs

  • Mathematica
    b[t_]:=Fibonacci[First[t]] a[n_]:=Apply[Times, Map[b, FactorInteger[n]]] (* Esa Peuha, Oct 26 2005 *)
    Table[Times@@(Fibonacci[#]&/@FactorInteger[n][[All,1]]),{n,60}] (* Harvey P. Dale, May 31 2019 *)
  • Sage
    [1]+[prod([fibonacci(p) for p in prime_factors(n)]) for n in range(2,53)] # Danny Rorabaugh, Apr 03 2015

Formula

Multiplicative with a(p^e) = F(p). - Franklin T. Adams-Watters, Jun 05 2006

Extensions

More terms from Esa Peuha (esa.peuha(AT)helsinki.fi), Oct 26 2005
Showing 1-3 of 3 results.