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 1-4 of 4 results.

A067276 Determinant of n X n matrix containing the first n^2 primes in increasing order.

Original entry on oeis.org

2, -1, -78, 880, -4656, -14304, -423936, 8342720, 711956736, -615707136, 21057138688, -4663930678272, 211912980656128, -9178450735677440, 40005919124799488, 83013253447139328, -8525111273818357760, -800258888289188708352, -15170733077495639179264
Offset: 1

Views

Author

Rick L. Shepherd, Feb 21 2002

Keywords

Comments

The first column contains the first n primes in increasing order, the second column contains the next n primes in increasing order, etc. Equivalently, first row contains first n primes in increasing order, second row contains next n primes in increasing order, etc. Sequences of determinants of matrices specifically containing primes include A024356 (Hankel matrix), A067549 (first n primes on diagonal, other elements 1), A066933 (cyclic permutations of first n primes in each row) and A067551 (first n primes on diagonal, other elements 0).

Examples

			a(3) = -78 because det[[2,7,17],[3,11,19],[5,13,23]] = -78 (= det[[2,3,5],[7,11,13],[17,19,23]], the determinant of the transpose.).
		

Crossrefs

Programs

  • Magma
    [ Determinant( Matrix(n, n, [ NthPrime(k): k in [1..n^2] ]) ): n in [1..19] ]; // Klaus Brockhaus, May 12 2010
    
  • Maple
    seq(LinearAlgebra:-Determinant(Matrix(n,n,(i,j) -> ithprime(n*(i-1)+j))),n=1..20); # Robert Israel, Jul 12 2017
  • Mathematica
    Table[ Det[ Partition[ Array[Prime, n^2], n]], {n, 19}] (* Robert G. Wilson v, May 26 2006 *)
  • PARI
    for(n=1,20,k=0; m=matrix(n,n,x,y, prime(k=k+1)); print1(matdet(m), ", ")) /* The matrix initialization command above fills columns first: Variables (such as) x and y take on values 1 through n for rows and columns, respectively, with x changing more rapidly and they must be specified even though the 5th argument is not an explicit function of them here. */
    
  • Python
    from sympy.matrices import Matrix
    from sympy import sieve
    def a(n):
        sieve.extend_to_no(n**2)
        return Matrix(n, n, sieve[1:n**2+1]).det()
    print([a(n) for n in range(1, 20)]) # Indranil Ghosh, Jul 31 2017

A119895 Numbers k such that 2^k, 3^k, 5^k, 7^k, 11^k and 13^k have even digit sum.

Original entry on oeis.org

90, 168, 185, 229, 242, 447, 470, 503, 552, 657, 684, 758, 804, 811, 1000, 1113, 1126, 1182, 1402, 1410, 1412, 1420, 1546, 1566, 1638, 1655, 1663, 1790, 2066, 2180, 2232, 2275, 2362, 2390, 2416, 2504, 2585, 2670, 2721, 2725, 2803, 2814, 2902, 2911, 2928
Offset: 1

Views

Author

Zak Seidov, May 26 2006

Keywords

Crossrefs

Programs

  • Mathematica
    Select[Range[3000],AllTrue[Total[IntegerDigits[#]]&/@(Prime[ Range[ 6]]^#), EvenQ]&] (* The program uses the AllTrue function from Mathematica version 10 *) (* Harvey P. Dale, May 10 2018 *)

A119897 Numbers k such that 2^k, 3^k, 5^k, 7^k, 11^k, 13^k, 17^k and 19^k have even digit sum.

Original entry on oeis.org

552, 657, 811, 1412, 1655, 2390, 2504, 2721, 2803, 2902, 3002, 3060, 3135, 3393, 3660, 4414, 4500, 4547, 4750, 4787, 4824, 5036, 5539, 5906, 6782, 7728, 8650, 9263, 9873, 9953, 10367, 10643, 10684, 10723, 11369, 11647, 11867, 11954
Offset: 1

Views

Author

Zak Seidov, May 26 2006

Keywords

Crossrefs

Programs

  • Mathematica
    edsQ[n_]:=AllTrue[Prime[Range[8]]^n,EvenQ[Total[IntegerDigits[#]]]&]; Select[ Range[12000],edsQ] (* The program uses the AllTrue function from Mathematica version 10 *) (* Harvey P. Dale, May 10 2017 *)

Extensions

More terms from Harvey P. Dale, May 10 2017

A119896 Numbers k such that 2^k, 3^k, 5^k, 7^k, 11^k, 13^k and 17^k have even digit sum.

Original entry on oeis.org

90, 185, 447, 470, 503, 552, 657, 758, 804, 811, 1182, 1412, 1546, 1566, 1638, 1655, 2275, 2390, 2504, 2670, 2721, 2803, 2814, 2902, 2928, 3002, 3060, 3087, 3135, 3393, 3660, 3751
Offset: 1

Views

Author

Zak Seidov, May 26 2006

Keywords

Crossrefs

Showing 1-4 of 4 results.