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.

A265110 Partial row products of table A027746, prime factors with repetition.

Original entry on oeis.org

1, 2, 3, 2, 4, 5, 2, 6, 7, 2, 4, 8, 3, 9, 2, 10, 11, 2, 4, 12, 13, 2, 14, 3, 15, 2, 4, 8, 16, 17, 2, 6, 18, 19, 2, 4, 20, 3, 21, 2, 22, 23, 2, 4, 8, 24, 5, 25, 2, 26, 3, 9, 27, 2, 4, 28, 29, 2, 6, 30, 31, 2, 4, 8, 16, 32, 3, 33, 2, 34, 5, 35, 2, 4, 12, 36
Offset: 1

Views

Author

Reinhard Zumkeller, Dec 01 2015

Keywords

Comments

T(n,1) = A020639(n); T(n,A001222(n)) = n.

Examples

			.   n |   T(n,*)       |   A027746(n,*)
. ----+----------------+----------------
.   1 |   1            |   1
.   2 |   2            |   2
.   3 |   3            |   3
.   4 |   2, 4         |   2, 2
.   5 |   5            |   5
.   6 |   2, 6         |   2, 3
.   7 |   7            |   7
.   8 |   2, 4, 8      |   2, 2, 2
.   9 |   3, 9         |   3, 3
.  10 |   2, 10        |   2, 5
.  11 |   11           |   11
.  12 |   2, 4, 12     |   2, 2, 3
.  13 |   13           |   13
.  14 |   2, 14        |   2, 7
.  15 |   3, 15        |   3, 5
.  16 |   2, 4, 8, 16  |   2, 2, 2, 2
.  17 |   17           |   17
.  18 |   2, 6, 18     |   2, 3, 3
.  19 |   19           |   19
.  20 |   2, 4, 20     |   2, 2, 5
		

Crossrefs

Cf. A027746, A175943, A001222 (row lengths), A020639.

Programs

  • Haskell
    a265110 n k = a265110_tabf !! (n-1) !! (k-1)
    a265110_row n = a265110_tabf !! (n-1)
    a265110_tabf = map (scanl1 (*)) a027746_tabf
  • Mathematica
    Table[FoldList[Times, Flatten[FactorInteger[n] /. {p_, e_} /; e > 0 :> ConstantArray[p, e]]], {n, 37}] // Flatten (* Michael De Vlieger, Apr 28 2017 *)

Formula

T(n,k) = product(A027747(n,k): k = 1 .. A001221(n)).