1,2

A prime number appears in a column at every A130290:th row from the (A130290+1):th row onwards. The prime numbers are so to say equidistantly distributed in the columns. A130290 is essentially A005097. Counting terms > 1 in the rows gives A046886.

T(n,k) = if mod(A002445;A000040)=0 then A000040 else 1.

First few rows of the triangle and row products are:

1 = 1

2*3 = 6

2*3*5 = 30

2*3*1*7 = 42

2*3*5*1*1 = 30

2*3*1*1*11*1 = 66

2*3*5*7*1*13*1 = 2730

Cf. A002445, A046886, A130290, A005097.

Sequence in context: A078198 A098235 A114868 this_sequence A112484 A124459 A046147

Adjacent sequences: A138236 A138237 A138238 this_sequence A138240 A138241 A138242

nonn,tabl

Mats Granvik (mgranvik(AT)abo.fi), Mar 07 2008