A073915 Triangle read by rows in which the n-th row contains the first n numbers with n divisors.

1, 2, 3, 4, 9, 25, 6, 8, 10, 14, 16, 81, 625, 2401, 14641, 12, 18, 20, 28, 32, 44, 64, 729, 15625, 117649, 1771561, 4826809, 24137569, 24, 30, 40, 42, 54, 56, 66, 70, 36, 100, 196, 225, 256, 441, 484, 676, 1089, 48, 80, 112, 162, 176, 208, 272, 304, 368, 405

Offset

1,2

Comments

The first row contains the 1. The 2nd row contains the beginning of A000040. The 3rd contains the beginning of A001248, the 4th through 7th A030513 to A030516. The 8th through 20th rows come from A030626 to A030638. - R. J. Mathar, Mar 23 2007

Links

T. D. Noe, Rows n = 1..100 of triangle, flattened

Example

1;
2,3;
4,9,25;
6,8,10,14;
16,81,625,2401,14641;
...

Mathematica

d = Table[Length[Divisors[n]], {n, 2000}]; t = {}; n = 0; ok = True; While[ok, n++; If[PrimeQ[n], AppendTo[t, Prime[Range[n]]^(n - 1)], c = Flatten[Position[d, n, 1, n]]; If[Length[c] >= n, AppendTo[t, c], ok = False]]]; Flatten[t] (* T. D. Noe, Jun 23 2013 *)

Crossrefs

Cf. A073916.

Sequence in context: A088220 A333431 A085612 * A076381 A282571 A063455

Adjacent sequences: A073912 A073913 A073914 * A073916 A073917 A073918

Keyword

nonn,tabl

Author

Amarnath Murthy, Aug 18 2002

Extensions

Corrected and extended by Sascha Kurz, Jan 28 2003

Status

approved