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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A356964 Replace 2^k in binary expansion of n with tribonacci(k+3) (where tribonacci corresponds to A000073).

Original entry on oeis.org

0, 1, 2, 3, 4, 5, 6, 7, 7, 8, 9, 10, 11, 12, 13, 14, 13, 14, 15, 16, 17, 18, 19, 20, 20, 21, 22, 23, 24, 25, 26, 27, 24, 25, 26, 27, 28, 29, 30, 31, 31, 32, 33, 34, 35, 36, 37, 38, 37, 38, 39, 40, 41, 42, 43, 44, 44, 45, 46, 47, 48, 49, 50, 51, 44, 45, 46, 47
Offset: 0

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Author

Rémy Sigrist, Sep 06 2022

Keywords

Comments

This sequence is to tribonacci numbers (A000073) what A022290 is to Fibonacci numbers (A000045).
For any k >= 0, k appears A117546(k) times in this sequence.

Examples

			For n = 9:
- 9 = 2^3 + 2^0,
- so a(9) = A000073(3+3) + A000073(0+3) = 7 + 1 = 8.
		

Crossrefs

Programs

  • PARI
    a(n) = { my (v=0, k); while (n, n-=2^k=valuation(n,2); v+=([0,1,0; 0,0,1; 1,1,1]^(3+k))[2,1]); return (v); }
    
  • Python
    def A356964(n):
        a, b, c, s = 1,2,4,0
        for i in bin(n)[-1:1:-1]:
            s += int(i)*a
            a, b, c = b, c, a+b+c
        return s # Chai Wah Wu, Sep 10 2022

Formula

a(A003726(n+1)) = n.
a(A003796(n+1)) = n.

A356965 a(n) is the sum of the tribonacci numbers in common in the greedy and lazy tribonacci representations of n.

Original entry on oeis.org

0, 1, 2, 3, 4, 5, 6, 0, 8, 9, 10, 11, 12, 0, 1, 15, 16, 17, 18, 19, 13, 21, 22, 23, 0, 1, 2, 3, 28, 29, 30, 24, 32, 33, 34, 35, 36, 24, 25, 39, 40, 41, 42, 43, 0, 1, 2, 3, 4, 5, 6, 7, 52, 53, 54, 55, 56, 44, 45, 59, 60, 61, 62, 63, 57, 65, 66, 67, 44, 45, 46
Offset: 0

Views

Author

Rémy Sigrist, Sep 06 2022

Keywords

Comments

This sequence is to tribonacci numbers (A000073) what A356771 is to Fibonacci numbers (A000045).

Examples

			For n = 58:
- with T = A000073,
- the greedy representation of 58 is: T(9) + T(7) + T(3),
- the lazy representation of 58 is: T(9) + T(6) + T(5) + T(4) + T(3),
- so a(59) = T(9) + T(3) = 45.
		

Crossrefs

Programs

  • PARI
    See Links section.

Formula

a(n) = A356964(A003796(n+1) AND A003726(n+1)) (where AND denotes the bitwise AND operator).
a(n) <= n with equality iff n belongs to A356899.
a(n) = 0 iff n belongs to A356966.

A356966 Numbers with no common terms in their greedy and lazy tribonacci representations.

Original entry on oeis.org

0, 7, 13, 24, 44, 81, 88, 149, 156, 162, 274, 287, 298, 504, 511, 528, 548, 927, 934, 940, 971, 1008, 1015, 1705, 1718, 1729, 1786, 1793, 1854, 1861, 1867, 3136, 3143, 3160, 3180, 3285, 3292, 3298, 3410, 3423, 3434, 5768, 5775, 5781, 5812, 5849, 5856, 6042
Offset: 1

Views

Author

Rémy Sigrist, Sep 06 2022

Keywords

Comments

Also numbers k such that the binary expansions of A003726(k+1) and A003796(k+1) have no common 1's.
Also positions of 0's in A356965.
This sequence is to tribonacci numbers (A000073) what A331467 is to Fibonacci numbers (A000045).
This sequence includes tribonacci numbers >= 7.

Examples

			With T = A000073:
- the greedy representation of 13 is: T(7),
- the lazy representation of 13 is: T(6) + T(5) + T(4),
- there are no common terms,
- so 13 belongs to this sequence.
		

Crossrefs

Programs

  • PARI
    See Links section.

A356974 Irregular triangle T(n, k) read by rows, n >= 0, k = 1..A117546(n); the n-th row contains the numbers m such that A356964(m) = n, in increasing order.

Original entry on oeis.org

0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 16, 15, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 32, 29, 33, 30, 34, 31, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 48, 47, 49, 50, 51, 52, 53, 54, 55, 56, 64, 57, 65, 58, 66, 59, 67, 60, 68, 61, 69, 62, 70
Offset: 0

Views

Author

Rémy Sigrist, Sep 07 2022

Keywords

Comments

This sequence is to tribonacci numbers (A000073) what A345101 is to Fibonacci numbers (A000045).
This sequence (when interpreted as a flat sequence) is a permutation of the nonnegative integers.

Examples

			Triangle begins:
     0   [0]
     1   [1]
     2   [2]
     3   [3]
     4   [4]
     5   [5]
     6   [6]
     7   [7, 8]
     8   [9]
     9   [10]
    10   [11]
    11   [12]
    12   [13]
    13   [14, 16]
    14   [15, 17]
		

Crossrefs

Programs

  • PARI
    See Links section.

Formula

T(n, 1) = A003796(n+1).
T(n, A117546(n)) = A003726(n+1).
Previous Showing 11-14 of 14 results.