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.

A065003 Not McNugget numbers.

Original entry on oeis.org

1, 2, 3, 4, 5, 7, 8, 10, 11, 13, 14, 16, 17, 19, 22, 23, 25, 28, 31, 34, 37, 43
Offset: 1

Views

Author

Karl Sabbagh (karl.sabbagh(AT)btinternet.com), Nov 01 2001

Keywords

Comments

A McNugget number has the form 6x + 9y + 20z for nonnegative integers x, y, z.
A214772(a(n)) = 0. - Reinhard Zumkeller, Jul 28 2012

References

  • Eric Weisstein, Concise Encyclopedia of Mathematics, p. 1151.

Links

Crossrefs

Cf. A214777 (complement).

Programs

  • Haskell
    import Data.List (elemIndices)
a065003 n = a065003_list !! n
a065003_list = elemIndices 0 $ map a214772 [0..43]
-- Reinhard Zumkeller, Jul 28 2012
  • Mathematica
    Select[Range[43], Length@FrobeniusSolve[{6, 9, 20}, #] == 0 &] (* Arkadiusz Wesolowski, Feb 20 2013 *)
  • PARI
    is(n)=forstep(k=n,6,-20,if(k%3==0, return(0)));n%20>0 \\ Charles R Greathouse IV, May 05 2013

A214777 McNugget numbers: numbers of the form 6*x + 9*y + 20*z for nonnegative integers x, y, z.

Original entry on oeis.org

0, 6, 9, 12, 15, 18, 20, 21, 24, 26, 27, 29, 30, 32, 33, 35, 36, 38, 39, 40, 41, 42, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86
Offset: 1

Views

Author

Reinhard Zumkeller, Jul 28 2012

Keywords

Comments

A214772(a(n)) > 0;
complement of A065003; all numbers greater than 43 are McNugget numbers: Frobenius(6,9,20) = 43.

Links

Crossrefs

Cf. A065003, A214772.

Programs

  • Haskell
    import Data.List (findIndices)
a214777 n = a214777_list !! (n-1)
a214777_list = findIndices (> 0) a214772_list
  • Mathematica
    CoefficientList[Series[- x (x^22 - x^21 + x^17 - x^16 + x^15 - x^14 + x^13 - x^12 + x^11 - x^10 + x^9 + x^8 - 2 x^7 + x^6 + x^5 + 3 x - 6)/(1 - x)^2, {x, 0, 70}], x] (* Vincenzo Librandi, Apr 27 2015 *)
  • Python
    def A214777(n): return (0, 6, 9, 12, 15, 18, 20, 21, 24, 26, 27, 29, 30, 32, 33, 35, 36, 38, 39, 40, 41, 42)[n-1] if n<23 else n+21 # Chai Wah Wu, Feb 24 2025

Formula

G.f.: -x^2*(x^22-x^21+x^17-x^16+x^15-x^14+x^13-x^12+x^11-x^10+x^9+x^8-2*x^7+x^6+x^5+3*x-6) / (x-1)^2. - Colin Barker, Dec 13 2012
a(n) = n + 21 for n >= 23. - Robert Israel, May 01 2015
Showing 1-2 of 2 results.

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