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.

A153734 Triangle T(n,k): T(n,k) gives the A153452(m_k) such that A056239(m_k) = n, [1<=k<=A000041(n)], sorted by m_k, read by rows. Sequence A060240 is this sequence's permutation.

Original entry on oeis.org

1, 1, 1, 1, 1, 2, 1, 1, 2, 3, 3, 1, 1, 4, 5, 5, 6, 4, 1, 1, 9, 5, 5, 5, 10, 16, 9, 10, 5, 1, 1, 6, 14, 14, 35, 15, 21, 21, 14, 20, 35, 14, 15, 6, 1, 1, 7, 20, 14, 21, 28, 56, 64, 70, 42, 14, 90, 35, 70, 56, 28, 35, 64, 20, 21, 7, 1
Offset: 0

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Author

Naohiro Nomoto, Dec 31 2008

Keywords

Comments

Lengths of rows are 1, 1, 2, 3, 5, 7, 11, 15, 22, 30,.... (A000041). Row sums give A000085.

Examples

			For n=4, A056239(7) = A056239(9) = A056239(10) = A056239(12) = A056239(16) = 4. Hence T(4,k) = A153452(m_k) = (1,2,3,3,1), where 1<=k<=5, m_k = 7,9,10,12,16.
Triangle T(n,k) begins:
  1;
  1;
  1, 1;
  1, 2, 1;
  1, 2, 3, 3, 1;
  1, 4, 5, 5, 6,  4,  1;
  1, 9, 5, 5, 5, 10, 16, 9, 10, 5, 1;
  ...
		

Crossrefs

Programs

  • Maple
    with(numtheory):
    g:= proc(n) option remember; `if`(n=1, 1,
          add(g(n/q*`if`(q=2, 1, prevprime(q))), q=factorset(n)))
        end:
    b:= proc(n, i) option remember; `if`(n=0 or i<2, [2^n],
           [seq(map(p->p*ithprime(i)^j, b(n-i*j, i-1))[], j=0..n/i)])
        end:
    T:= n-> map(g, sort(b(n, n)))[]:
    seq(T(n), n=0..10);  # Alois P. Heinz, Aug 09 2012
  • Mathematica
    g[n_] := g[n] = If[n == 1, 1, Sum[g[n/q*If[q == 2, 1, NextPrime[q, -1]]], {q, FactorInteger[n][[All, 1]]}]];
    b[n_, i_] := b[n, i] = If[n == 0 || i < 2, {2^n}, Flatten[Table[Map[ #*Prime[i]^j&, b[n - i*j, i - 1]], {j, 0, n/i}]]];
    T[n_] := g /@ Sort[b[n, n]];
    T /@ Range[0, 10] // Flatten (* Jean-François Alcover, Feb 16 2021, after Alois P. Heinz *)