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 1-5 of 5 results.

A112060 Square array A(x,y) = y-th natural number k for which A112049(k)=x and 0 if no such k exists; read by antidiagonals A(1,1), A(2,1), A(1,2), A(3,1), A(2,2), ...

Original entry on oeis.org

1, 2, 3, 5, 4, 11, 6, 7, 12, 24, 9, 8, 23, 35, 60, 10, 15, 36, 59, 155, 84, 13, 16, 47, 95, 275, 239, 144, 14, 19, 48, 119, 335, 575, 779, 180, 17, 20, 71, 120, 359, 659, 1499, 2855, 264, 18, 27, 72, 179, 419, 839, 1535, 4199, 5279, 420, 21, 28, 83, 204, 504
Offset: 1

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Author

Antti Karttunen, Aug 27 2005

Keywords

Comments

This is a permutation of natural numbers provided that the sequence A112046 contains only prime values [which is true] and every prime occurs infinitely many times there.

Examples

			The top left corner of the array:
   1,  2,  5,  6,  9, 10, ...
   3,  4,  7,  8, 15, 16, ...
  11, 12, 23, 36, 47, ...
		

Crossrefs

A112070(x, y) = 2*A(X, Y)+1. Transpose: A112061. Column 1: A112051. Row 1: A042963, Row 2: A112062, Row 3: A112063, Row 4: A112064, Row 5: A112065, Row 6: A112066, Row 7: A112067, Row 8: A112068, Row 9: A112069.
Cf. also A227196.

A227198 Odd terms in A227197.

Original entry on oeis.org

9, 15, 25, 33, 39, 49, 57, 63, 81, 87, 95, 105, 111, 119, 121, 129, 135, 145, 153, 159, 169, 177, 183, 201, 207, 215, 225, 231, 249, 255, 265, 273, 279, 289, 297, 303, 321, 327, 335, 345, 351, 361, 369, 375, 385, 393, 399, 417, 423, 441, 447, 455, 465, 471, 489
Offset: 1

Views

Author

Antti Karttunen, Jul 06 2013

Keywords

Comments

Gives all terms n for which A090368((n+1)/2) = A112046((n-1)/2).
Contains all odd squares. What else?

Crossrefs

Programs

  • PARI
    A227196(n) = for(k=1, n, if(kronecker(k, n)<1, return(k)))
    for(n=2,1000,if((0==kronecker(A227196(n),n)&&1==(n%2)),print1(n,", ")))

A227195 a(n) = one less than the first i >= 1 for which the Kronecker symbol K(i,n) is either 0 or -1. Or the maximal value u such that all K(1,n), K(2,n), ... up to K(u,n) have +1 as their values.

Original entry on oeis.org

1, 1, 1, 1, 1, 2, 1, 2, 1, 1, 1, 1, 1, 2, 1, 2, 1, 1, 1, 1, 1, 4, 1, 4, 1, 1, 1, 1, 1, 2, 1, 2, 1, 1, 1, 1, 1, 2, 1, 2, 1, 1, 1, 1, 1, 4, 1, 6, 1, 1, 1, 1, 1, 2, 1, 2, 1, 1, 1, 1, 1, 2, 1, 2, 1, 1, 1, 1, 1, 6, 1, 4, 1, 1, 1, 1, 1, 2, 1, 2, 1, 1, 1, 1, 1, 2, 1, 2, 1, 1, 1, 1, 1, 4, 1, 4, 1, 1, 1, 1, 1, 2, 1, 2
Offset: 2

Views

Author

Antti Karttunen, Jul 06 2013

Keywords

Comments

A112050 interleaved with A000012.

Crossrefs

Bisections: A112050 (for odd terms from 3 onward), A000012 (for all even terms).

Programs

Formula

a(n) = A227196(n)-1 for all n >= 2.

Extensions

Data section extended up to a(105) by Antti Karttunen, Nov 08 2018

A227197 Integers k for which the first non-one value of Kronecker symbols K(1,k), K(2,k), ..., K(u,k) is 0, not -1.

Original entry on oeis.org

2, 4, 6, 8, 9, 10, 12, 14, 15, 16, 18, 20, 22, 24, 25, 26, 28, 30, 32, 33, 34, 36, 38, 39, 40, 42, 44, 46, 48, 49, 50, 52, 54, 56, 57, 58, 60, 62, 63, 64, 66, 68, 70, 72, 74, 76, 78, 80, 81, 82, 84, 86, 87, 88, 90, 92, 94, 95, 96, 98, 100, 102, 104, 105, 106
Offset: 1

Views

Author

Antti Karttunen, Jul 06 2013

Keywords

Comments

Contains all even numbers >= 2. A227198 gives the odd terms.
Gives all k such that A020639(k) = A227196(k).

Crossrefs

Programs

  • PARI
    A227196(n) = for(k=1,n,if(kronecker(k,n)<1,return(k)))
    for(n=2,500,if((0==kronecker(A227196(n),n)),print1(n,", ")))

A227194 Natural numbers for which all sums Sum_{i=1..u} K(i/n) (with u ranging from 1 to n) are nonnegative, where K(i/n) is Kronecker symbol of i and n.

Original entry on oeis.org

1, 2, 3, 4, 6, 7, 9, 10, 11, 12, 14, 15, 16, 23, 24, 25, 26, 27, 30, 31, 34, 35, 36, 38, 39, 42, 44, 47, 48, 49, 54, 55, 56, 58, 59, 62, 63, 64, 66, 71, 74, 75, 76, 79, 81, 82, 83, 86, 87, 94, 95, 96, 100, 103, 106, 108, 110, 111, 114, 119, 120, 121, 130, 131
Offset: 1

Views

Author

Antti Karttunen, Jul 06 2013

Keywords

Crossrefs

Subsets: A095100, A095102 (gives the prime terms). Cf. A227196-A227198.

Programs

  • PARI
    firstdiving(n) = {s=0;for(k=1,n,s=s+kronecker(k,n);if(s<0,return(k)));return(0)}
    for(n=1,500,if((0==firstdiving(n)),print1(n,", ")))
Showing 1-5 of 5 results.