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.

A370129 Triangle read by rows: T(n,k) = A003415(A002110(n)+A002110(k)), 0 <= k <= n; arithmetic derivatives of the sums of two primorial numbers.

Original entry on oeis.org

1, 1, 4, 1, 12, 16, 1, 80, 60, 92, 1, 216, 540, 608, 704, 1, 3740, 3100, 4548, 6324, 8164, 568, 60080, 40060, 56292, 116208, 61768, 110752, 33975, 1021040, 1041768, 794468, 2415104, 1091004, 1357128, 1942844, 28300, 9789116, 29099520, 19722884, 18576860, 35347200, 35779644, 26575580, 37935056, 704080, 335024060
Offset: 0

Views

Author

Antti Karttunen, Feb 29 2024

Keywords

Comments

Apart from those positions (A014545) at the left edge where a(n) = 1, a(n) <= A087112(1+n) only at n=2, 4 and 5, i.e., never after the third row.

Examples

			Triangle begins as:
      1;
      1,       4;
      1,      12,       16;
      1,      80,       60,       92;
      1,     216,      540,      608,      704;
      1,    3740,     3100,     4548,     6324,     8164;
    568,   60080,    40060,    56292,   116208,    61768,   110752;
  33975, 1021040,  1041768,   794468,  2415104,  1091004,  1357128,  1942844;
  28300, 9789116, 29099520, 19722884, 18576860, 35347200, 35779644, 26575580, 37935056;
		

Crossrefs

Cf. A014545 (positions of 1's at the left edge), A087112.
Cf. also A024451 (arithmetic derivatives of primorials).

Programs

Formula

a(n) = A003415(A370121(n)).
For n, k >= 1, T(n,k) = A002110(k)*A370136(n,k) + A024451(k)*A370135(n,k).

A370134 Triangle read by rows: T(n,k) = A002110(n) + A002110(k), 1 <= k <= n; sums of two primorials > 1, not necessarily distinct.

Original entry on oeis.org

4, 8, 12, 32, 36, 60, 212, 216, 240, 420, 2312, 2316, 2340, 2520, 4620, 30032, 30036, 30060, 30240, 32340, 60060, 510512, 510516, 510540, 510720, 512820, 540540, 1021020, 9699692, 9699696, 9699720, 9699900, 9702000, 9729720, 10210200, 19399380, 223092872, 223092876, 223092900, 223093080, 223095180, 223122900, 223603380
Offset: 1

Views

Author

Antti Karttunen, Mar 07 2024

Keywords

Examples

			Triangle begins as:
        4;
        8,      12;
       32,      36,      60;
      212,     216,     240,     420;
     2312,    2316,    2340,    2520,    4620;
    30032,   30036,   30060,   30240,   32340,   60060;
   510512,  510516,  510540,  510720,  512820,  540540, 1021020;
  9699692, 9699696, 9699720, 9699900, 9702000, 9729720, 10210200, 19399380;
		

Crossrefs

A370121 without its leftmost column. Subsequence of A370132.
Cf. A088860 (right edge).

Programs

  • Mathematica
    nn = 20; MapIndexed[Set[P[First[#2] - 1], #1] &, FoldList[Times, 1, Prime@ Range[nn + 1]]]; Table[(P[n] + P[k]), {n, nn}, {k, n}] (* Michael De Vlieger, Mar 08 2024 *)
  • PARI
    A002110(n) = prod(i=1,n,prime(i));
    A370134(n) = { n--; my(c = (sqrtint(8*n + 1) - 1) \ 2); (A002110(1+c) + A002110(1+n - binomial(c + 1, 2))); };

Formula

For n >= 1, A276150(a(n)) = 2.

A370136 Triangle read by rows: T(n,k) = arithmetic derivative of ((A002110(n) + A002110(k)) / A002110(k)), 1 <= k <= n.

Original entry on oeis.org

1, 4, 1, 32, 5, 1, 55, 60, 12, 1, 1292, 195, 71, 16, 1, 22532, 2505, 841, 384, 9, 1, 382892, 102723, 8897, 8640, 191, 21, 1, 2469635, 3502740, 323328, 34133, 9980, 756, 24, 1, 111738812, 18755325, 10308201, 1568312, 50621, 5211, 371, 44, 1, 4853127108, 2003156919, 107924801, 178347008, 2376149, 251367, 6339, 672, 31, 1
Offset: 1

Views

Author

Antti Karttunen, Mar 07 2024

Keywords

Examples

			Triangle begins as:
          1;
          4,        1;
         32,        5,        1;
         55,       60,       12,       1;
       1292,      195,       71,      16,     1;
      22532,     2505,      841,     384,     9,    1;
     382892,   102723,     8897,    8640,   191,   21,   1;
    2469635,  3502740,   323328,   34133,  9980,  756,  24,  1;
  111738812, 18755325, 10308201, 1568312, 50621, 5211, 371, 44, 1;
		

Crossrefs

Programs

Formula

a(n) = A003415(A370135(n)).
Showing 1-3 of 3 results.