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.

Previous Showing 21-23 of 23 results.

A331924 Number of compositions (ordered partitions) of n into distinct composite parts.

Original entry on oeis.org

1, 0, 0, 0, 1, 0, 1, 0, 1, 1, 3, 0, 3, 2, 5, 3, 5, 2, 13, 10, 13, 11, 21, 16, 29, 25, 35, 55, 71, 62, 87, 100, 115, 155, 185, 197, 247, 378, 311, 495, 553, 674, 767, 1060, 1047, 1469, 1463, 1846, 2139, 3391, 2713, 4135, 4453, 5930, 6409, 8777
Offset: 0

Views

Author

Ilya Gutkovskiy, Feb 01 2020

Keywords

Examples

			a(14) = 5 because we have [14], [10, 4], [8, 6], [6, 8] and [4, 10].
		

Crossrefs

A341504 Number of ways to write n as an ordered sum of 10 nonprime numbers.

Original entry on oeis.org

1, 0, 0, 10, 0, 10, 45, 10, 100, 130, 135, 460, 390, 820, 1435, 1552, 3135, 4090, 5805, 9370, 12040, 17890, 25485, 33940, 48385, 65812, 87925, 121040, 160155, 212350, 283666, 368590, 482750, 628390, 806450, 1039382, 1327060, 1682860, 2134730, 2684320, 3364819
Offset: 10

Views

Author

Ilya Gutkovskiy, Feb 13 2021

Keywords

Crossrefs

Programs

  • Maple
    b:= proc(n, t) option remember;
          `if`(n=0, `if`(t=0, 1, 0), `if`(t<1, 0, add(
          `if`(isprime(j), 0, b(n-j, t-1)), j=1..n)))
        end:
    a:= n-> b(n, 10):
    seq(a(n), n=10..50);  # Alois P. Heinz, Feb 13 2021
  • Mathematica
    nmax = 50; CoefficientList[Series[Sum[Boole[!PrimeQ[k]] x^k, {k, 1, nmax}]^10, {x, 0, nmax}], x] // Drop[#, 10] &

A368873 Number of compositions (ordered partitions) of n into nonprime parts not greater than sqrt(n).

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 95, 131, 181, 250, 345, 476, 657, 907, 1252, 1728, 2385, 3292, 4544, 6272, 8657, 11949, 16493, 22765, 31422, 43371, 439373, 643932, 943728, 1383100, 2027032, 2970760, 4353861, 6380893, 9351653, 13705513, 20086406, 29438059
Offset: 0

Views

Author

Ilya Gutkovskiy, Jan 08 2024

Keywords

Crossrefs

Programs

  • Maple
    b:= proc(n, t) option remember; `if`(n=0, 1, add(
         `if`(isprime(j), 0, b(n-j, t)), j=1..min(n, t)))
        end:
    a:= n-> b(n, floor(sqrt(n))):
    seq(a(n), n=0..47);  # Alois P. Heinz, Jan 13 2024
  • Mathematica
    Table[SeriesCoefficient[1/(1 - Sum[Boole[!PrimeQ[k]] x^k, {k, 1, Floor[Sqrt[n]]}]), {x, 0, n}], {n, 0, 47}]
Previous Showing 21-23 of 23 results.