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.

A374959 a(n) is the least k such that binomial(A349958(n), k) is a multiple of n.

Original entry on oeis.org

0, 1, 1, 1, 1, 2, 1, 1, 1, 2, 1, 2, 1, 2, 2, 1, 1, 2, 1, 3, 2, 4, 1, 3, 1, 2, 1, 2, 1, 3, 1, 1, 3, 2, 3, 2, 1, 4, 2, 3, 1, 3, 1, 3, 2, 8, 1, 5, 1, 2, 2, 6, 1, 4, 2, 3, 2, 2, 1, 3, 1, 2, 4, 1, 4, 4, 1, 2, 6, 4, 1, 5, 1, 2, 2, 4, 5, 2, 1, 3, 1, 2, 1, 3, 3, 4, 3
Offset: 1

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Author

Rémy Sigrist, Jul 25 2024

Keywords

Examples

			For n = 12: the first multiple of 12 in Pascal's triangle appears in row 9; this row contains: 1, 9, 36, 84, 126, 126, 84, 36, 9, 1; the first multiple of 12 (36), appears at (0-based) index 2; so a(12) = 2.
		

Crossrefs

Programs

  • PARI
    a(n) = { my (r = [1 % n], j); for (i = 0, oo, if (vecmin(r, &j)==0, return (j-1), r = (concat(0, r) + concat(r, 0)) % n;);); }
    
  • Python
    from math import comb
    def A374959(n): return next(k for j in range(n+1) for k in range(j+1) if not (comb(j,k) % n)) # Chai Wah Wu, Jul 30 2024

A375082 a(n) = binomial(A349958(n),A374959(n))/n.

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 3, 1, 2, 1, 1, 1, 2, 1, 1, 1, 15, 1, 5, 1, 3, 1, 1, 1, 4, 1, 1, 5, 4, 1, 1, 1, 102, 2, 3, 1, 2, 1, 5, 1, 10659, 1, 91, 1, 6, 3, 33, 1, 325, 1, 1, 3, 7, 1, 2, 1, 8, 2, 1, 11, 5, 1, 2, 1463, 1, 1, 11, 1, 9, 4, 51, 6, 1, 1, 7, 1
Offset: 1

Views

Author

Pontus von Brömssen, Jul 29 2024

Keywords

Crossrefs

Programs

  • Python
    from math import comb
    def A375082(n): return next(a for a, b in (divmod(comb(j,k),n) for j in range(n+1) for k in range(j+1)) if not b) # Chai Wah Wu, Jul 30 2024

A375083 Numbers k such that k is not the first multiple of k that appears in Pascal's triangle (read by rows), i.e., such that A375082(k) > 1.

Original entry on oeis.org

12, 14, 18, 22, 24, 26, 30, 33, 34, 38, 39, 40, 42, 44, 46, 48, 50, 51, 52, 54, 57, 58, 60, 62, 63, 65, 66, 68, 69, 72, 74, 75, 76, 77, 80, 82, 85, 86, 87, 88, 90, 92, 93, 94, 95, 96, 98, 99, 100, 102, 104, 105, 106, 108, 110, 111, 112, 114, 115, 116, 117, 118
Offset: 1

Views

Author

Pontus von Brömssen, Jul 29 2024

Keywords

Crossrefs

Programs

  • PARI
    isok(k) = for (i=1, k-1, for (j=1, i, my(b=binomial(i, j)); if (((b % k) == 0), return(b!=k)););); \\ Michel Marcus, Jul 30 2024
    
  • Python
    from itertools import count, islice
    from math import comb
    def A375083_gen(): # generator of terms
        return filter(lambda n:next(c for c in (comb(j,k) for j in range(n+1) for k in range(j+1)) if not c%n)>n, count(1))
    A375083_list = list(islice(A375083_gen(),20)) # Chai Wah Wu, Jul 30 2024
Showing 1-3 of 3 results.