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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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

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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).

A374124 a(n) = A113177(n) mod 360, where A113177 is fully additive with a(p) = Fibonacci(p).

Original entry on oeis.org

0, 1, 2, 2, 5, 3, 13, 3, 4, 6, 89, 4, 233, 14, 7, 4, 157, 5, 221, 7, 15, 90, 217, 5, 10, 234, 6, 15, 149, 8, 229, 5, 91, 158, 18, 6, 17, 222, 235, 8, 301, 16, 77, 91, 9, 218, 73, 6, 26, 11, 159, 235, 293, 7, 94, 16, 223, 150, 161, 9, 161, 230, 17, 6, 238, 92, 293, 159, 219, 19, 289, 7, 73, 18, 12, 223, 102, 236, 301
Offset: 1

Views

Author

Antti Karttunen, Jun 30 2024

Keywords

Crossrefs

Cf. A373585 (antiparity of terms), A373586 (indices of even terms), A373587 (of odd terms), A374052 (of multiples of 3).
Cf. also A372576, A374123, A374125.

Programs

  • PARI
    A113177(n) = if(n<=1, 0, my(f=factor(n)); sum(i=1, #f~, f[i, 2]*fibonacci(f[i,1])));
    A374124(n) = (A113177(n)%360);

A374123 a(n) = A328768(n) mod 360, where A328768 is the first primorial based variant of the arithmetic derivative.

Original entry on oeis.org

0, 0, 1, 2, 4, 6, 7, 30, 12, 12, 17, 210, 20, 150, 67, 28, 32, 150, 33, 30, 44, 104, 71, 210, 52, 60, 313, 54, 148, 150, 71, 30, 80, 292, 317, 192, 84, 210, 79, 116, 108, 210, 229, 330, 164, 114, 83, 150, 128, 60, 145, 124, 292, 210, 135, 36, 324, 128, 329, 330, 172, 30, 91, 354, 192, 108, 257, 30, 308, 316, 59, 210
Offset: 0

Views

Author

Antti Karttunen, Jun 30 2024

Keywords

Crossrefs

Cf. A042965 (indices of even terms), A016825 (of odd terms), A152822 (antiparity of terms), A373992 (indices of multiples of 3).
Cf. also A372576, A374124, A374125.

Programs

  • PARI
    A002110(n) = prod(i=1,n,prime(i));
    A328768(n) = if(n<=1, 0, my(f=factor(n)); n*sum(i=1, #f~, f[i, 2]*A002110(primepi(f[i,1])-1)/f[i, 1]));
    A374123(n) = (A328768(n)%360);

A379115 a(n) = A328845(n) mod 5, where A328845 is the first Fibonacci based variant of arithmetic derivative.

Original entry on oeis.org

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

Views

Author

Antti Karttunen, Dec 15 2024

Keywords

Crossrefs

Cf. A010874, A328845, A374125, A374205, A379116 (positions of 0's), A379117 (their characteristic function).

Programs

  • Mathematica
    A379115[n_] := If[n <= 1, 0, Mod[n*Total[MapApply[#2*Fibonacci[#]/# &, FactorInteger[n]]], 5]];
    Array[A379115, 100, 0] (* Paolo Xausa, Dec 16 2024 *)
  • PARI
    A379115(n) = if(n<=1, 0, my(f=factor(n)); (n*sum(i=1, #f~, f[i, 2]*fibonacci(f[i,1])/f[i, 1]))%5);

Formula

a(n) = A010874(A328845(n)) = A010874(A374125(n)).
Showing 1-4 of 4 results.