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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A275198 Triangle, read by rows, formed by reading Pascal's triangle (A007318) mod 14.

Original entry on oeis.org

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

Views

Author

Ilya Gutkovskiy, Aug 11 2016

Keywords

Examples

			Triangle begins:
                      1,
                    1,  1,
                  1,  2,  1,
                1,  3,  3,  1,
              1,  4,  6,  4,  1,
            1,  5, 10, 10,  5,  1,
          1,  6,  1,  6,  1,  6,  1,
        1,  7,  7,  7,  7,  7,  7,  1,
      1,  8,  0,  0,  0,  0,  0,  8,  1,
    1,  9,  8,  0,  0,  0,  0,  8,  9,  1,
  1, 10,  3,  8,  0,  0,  0,  8,  3, 10,  1,
  ...
		

Crossrefs

Sequences based on the triangles formed by reading Pascal's triangle mod m: A047999 (m = 2), A083093 (m = 3), A034931 (m = 4), A095140 (m = 5), A095141 (m = 6), A095142 (m = 7), A034930 (m = 8), A095143 (m = 9), A008975 (m = 10), A095144 (m = 11), A095145 (m = 12), (this sequence) (m = 14), A034932 (m = 16).

Programs

  • Mathematica
    Mod[Flatten[Table[Binomial[n, k], {n, 0, 14}, {k, 0, n}]], 14]
  • Python
    from math import comb, isqrt
    from sympy.ntheory.modular import crt
    def A275198(n):
        w, c = n-((r:=(m:=isqrt(k:=n+1<<1))-(k<=m*(m+1)))*(r+1)>>1), 1
        d = int(not ~r & w)
        while True:
            r, a = divmod(r,7)
            w, b = divmod(w,7)
            c = c*comb(a,b)%7
            if r<7 and w<7:
                c = c*comb(r,w)%7
                break
        return crt([7,2],[c,d])[0] # Chai Wah Wu, May 01 2025

Formula

T(n, k) = binomial(n, k) mod 14.
a(n) = A070696(A007318(n)).

A126054 Exponents p of the Mersenne primes 2^p - 1 (see A000043) read mod 14.

Original entry on oeis.org

2, 3, 5, 7, 13, 3, 5, 3, 5, 5, 9, 1, 3, 5, 5, 5, 13, 11, 11, 13, 1, 1, 13, 1, 1, 11, 5, 3, 1, 1, 1, 13, 1, 13, 5, 3, 9, 5, 9, 1, 11, 5, 1, 9, 9, 11, 1, 5
Offset: 1

Views

Author

Artur Jasinski, Dec 17 2006

Keywords

Crossrefs

Programs

  • Mathematica
    Mod[MersennePrimeExponent[Range[47]],14] (* Harvey P. Dale, Aug 12 2021 *)

Formula

a(n) = A070696(A000043(n)). - Michel Marcus, Apr 07 2018

Extensions

a(45)-a(47) from Ivan Panchenko, Apr 08 2018
a(48) from Amiram Eldar, Oct 15 2024
Showing 1-2 of 2 results.