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 1-2 of 2 results.

A356327 Replace 2^k in binary expansion of n with A039834(1+k).

Original entry on oeis.org

0, 1, -1, 0, 2, 3, 1, 2, -3, -2, -4, -3, -1, 0, -2, -1, 5, 6, 4, 5, 7, 8, 6, 7, 2, 3, 1, 2, 4, 5, 3, 4, -8, -7, -9, -8, -6, -5, -7, -6, -11, -10, -12, -11, -9, -8, -10, -9, -3, -2, -4, -3, -1, 0, -2, -1, -6, -5, -7, -6, -4, -3, -5, -4, 13, 14, 12, 13, 15, 16
Offset: 0

Views

Author

Rémy Sigrist, Aug 03 2022

Keywords

Comments

This sequence has similarities with A022290, and is related to negaFibonacci representations.

Examples

			For n = 13:
- 13 = 2^3 + 2^2 + 2^0,
- so a(13) = A039834(4) + A039834(3) + A039834(1) = -3 + 2 + 1 = 0.
		

Crossrefs

Programs

  • Mathematica
    Table[Reverse[#].Fibonacci[-Range[Length[#]]] &@ IntegerDigits[n, 2], {n, 0, 69}] (* Rémy Sigrist, Aug 05 2022 *)
  • PARI
    a(n) = { my (v=0, k); while (n, n-=2^k=valuation(n, 2); v+=fibonacci(-1-k)); return (v) }
    
  • Python
    from sympy import fibonacci
    def A356327(n): return sum(fibonacci(-a)*int(b) for a, b in enumerate(bin(n)[:1:-1],start=1)) # Chai Wah Wu, Aug 31 2022

Formula

a(n) = Sum_{k>=0} A030308(n,k)*A039834(1+k).
a(A215024(n)) = n.
a(A215025(n)) = -n.
a(A003714(n)) = A309076(n).
Empirically:
- a(n) = 0 iff n = 0 or n belongs to A072197,
- a(n) = 1 iff n belongs to A020989,
- a(2*A215024(n)) = -A000201(n) for n > 0,
- a(3*A215024(n)) = -A060143(n),
- a(floor(A215024(n)/2)) = -A060143(n),
- a(4*A215024(n)) = A001950(n) for n > 0,
- a(floor(A215024(n)/4)) = A189663(n) for n > 0,
- a(2*A215025(n)) = A026351(n),
- a(3*A215025(n)) = A019446(n) for n > 0,
- a(floor(A215025(n)/2)) = A019446(n) for n > 0,
- a(4*A215025(n)) = -A004957(n),
- a(floor(A215025(n)/4)) = -A060144(n+1) for n >= 0.

A356326 The terms in the negaFibonacci representation of a(n) are the terms in common in the negaFibonacci representations of n and -n.

Original entry on oeis.org

0, 0, 0, 0, -1, 0, 0, 0, 0, -1, -3, -3, -1, 0, 0, 0, 0, 4, 0, 0, 0, 0, -1, -3, -3, -1, -8, -8, -8, -8, -1, -3, -3, -1, 0, 0, 0, 0, 4, 0, 0, 0, 0, 12, 10, 10, 12, 0, 0, 0, 0, 4, 0, 0, 0, 0, -1, -3, -3, -1, -8, -8, -8, -8, -1, -3, -3, -1, -21, -21, -21, -21, -17
Offset: 0

Views

Author

Rémy Sigrist, Aug 03 2022

Keywords

Examples

			For n = 11:
- using F(-k) = A039834(k):
- 11 = F(-1) + F(-4) + F(-7),
- -11 = F(-4) + F(-6),
- so a(11) = F(-4) = -3.
		

Crossrefs

Programs

  • PARI
    See Links section.

Formula

a(n) = 0 iff n belongs to A062877.
a(n) = A356327(A215024(n) AND A215025(n)) (where AND denotes the bitwise AND operator).
Empirically:
- a(A000045(k)+m) = a(A000045(k+1)-m) for k >= 0, m = 0..A000045(k+1)-A000045(k).
Showing 1-2 of 2 results.