A119843 A119842(n) sets a new record.

1, 36, 72, 120, 144, 180, 420, 720, 1080, 1680, 2520, 6300, 9240

Offset

1,2

Comments

a(9) is greater than 960.

Links

Table of n, a(n) for n=1..13.

Mathematica

b[s_, t_] := b[s, t] = If[Length[s] < 1, 1, Sum[If[Mod[PrimeOmega[x], 2] == 1 - t && Length[Select[s, Mod[#, x] == 0 &]] == 1, b[s~Complement~{x}, 1 - t], 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][[2 ;; -2]], Mod[PrimeOmega[m], 2]]]; Reap[For[record = 0; k = 1, k < 10^4, k++, If[a[k] > record, record = a[k]; Print[k, " ", a[k]]; Sow[k]]]][[2, 1]] (* Jean-François Alcover, Mar 03 2016, after Alois P. Heinz *)

Crossrefs

Subset of A119845. Cf. A119844.

Sequence in context: A369374 A031479 A153642 * A339979 A322657 A364930

Adjacent sequences: A119840 A119841 A119842 * A119844 A119845 A119846

Keyword

nonn

Author

Antti Karttunen, Jun 04 2006

Extensions

a(9)-a(13) from Alois P. Heinz, Feb 26 2016

Status

approved