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 1-2 of 2 results.

A119500 Numbers n such that A114717(n) sets a new record.

Original entry on oeis.org

1, 6, 12, 24, 30, 60, 120, 180, 240, 360, 420, 720, 840, 1260, 1680, 2520, 4620, 5040, 7560, 9240
Offset: 1

Views

Author

Antti Karttunen, May 26 2006

Keywords

Comments

This sequence gives yet another list of "increasingly compound" numbers.

Crossrefs

Cf. A119499, A018894. Subset of A119840.

Programs

  • Mathematica
    b[s_] := b[s] = If[Length[s] < 2, 1, Sum[If[Length[Select[s, Mod[#, x] == 0 &]] == 1, b[Complement[s, {x}]], 0], {x, s}]]; a[n_] := a[n] = Module[{l, m}, l = Sort[FactorInteger[n], #1[[2]] > #2[[2]] &]; m = Product[Prime[i ]^l[[i]][[2]], {i, 1, Length[l]}]; b[Divisors[m] // Rest // Most]]; A119500 = Reap[For[record = 0; k = 1, k < 10^4, k++, ak = a[k]; If[ak > record, record = ak; Print[k, " ", ak]; Sow[k]]]][[2, 1]] (* Jean-François Alcover, Mar 03 2016, after Alois P. Heinz *)

Extensions

a(11)-a(17) from Alois P. Heinz, Aug 06 2012
a(18)-a(20) from Alois P. Heinz, Feb 25 2016

A119841 Distinct values in A114717 in order of appearance.

Original entry on oeis.org

1, 2, 5, 14, 48, 42, 2452, 462, 132, 183958, 6006, 4877756, 429, 1680384, 24024, 17454844, 87516, 20071150430, 1430, 409158464142, 1662804, 1941406508, 1385670, 129586764260850, 4862, 269333638458151764, 140229804, 6405442434150, 242201554680, 6708527580006468
Offset: 1

Views

Author

Antti Karttunen, May 26 2006

Keywords

Crossrefs

a(n) = A114717(A119840(n)). Cf. A119499.

Programs

  • Mathematica
    b[s_] := b[s] = If[Length[s] < 2, 1, Sum[If[Length[Select[s, Mod[#, x] == 0 &]] == 1, b[Complement[s, {x}]], 0], {x, s}]]; a[n_] := a[n] = Module[{l, m}, l = Sort[FactorInteger[n], #1[[2]] > #2[[2]] &]; m = Product[Prime[ i]^l[[i]][[2]], {i, 1, Length[l]}]; b[Divisors[m] // Rest // Most]]; A119841 = Reap[For[k = 1, k < 2000, k++, If[FreeQ[Array[a, k - 1], a[k]], Print[k, " ", a[k]]; Sow[a[k]]]]][[2, 1]] (* Jean-François Alcover, Mar 03 2016, after Alois P. Heinz *)

Extensions

a(19)-a(30) from Alois P. Heinz, Aug 06 2012
Showing 1-2 of 2 results.