A121281 Triangle T(n,k) read by rows: T(n,0) = A002110(n) and T(n,k) = A002110(n)/prime(k) for 1<=k<=n.

1, 2, 1, 6, 3, 2, 30, 15, 10, 6, 210, 105, 70, 42, 30, 2310, 1155, 770, 462, 330, 210, 30030, 15015, 10010, 6006, 4290, 2730, 2310, 510510, 255255, 170170, 102102, 72930, 46410, 39270, 30030, 9699690, 4849845, 3233230, 1939938, 1385670, 881790, 746130, 570570, 510510

Offset: 0

Author

Philippe Deléham, Aug 24 2006

Keywords

• nonn
• tabl

Examples

			Triangle begins
1;
2, 1;
6, 3, 2;
30, 15, 10, 6;
210, 105, 70, 42, 30;
		

Links

• Reinhard Zumkeller, Rows n = 0..120 of triangle, flattened

Crossrefs

Cf. A000040, A002110, A024528, A070826.

Programs

Haskell

a121281 n k = a121281_tabl !! n !! k
a121281_row n = a121281_tabl !! n
a121281_tabl = [1] : f [1] a000040_list where
   f xs@(x:_) (p:ps) = ys : f ys ps where ys = (map (* p) xs) ++ [x]
-- Reinhard Zumkeller, Nov 20 2015

PARI

tabl(nn) = {for (n=0, nn, pr = prod(i=1, n, prime(i)); for (k=0, n, if (k==0, v = pr, v = pr/prime(k)); print1(v, ", ");); print(););} \\ Michel Marcus, Apr 06 2015

Formula

Sum_{0<=k<=n} T(n,k) = A024528(n).

T(n+1,k) = prime(n+1) * T(n,k) for k=0..n and T(n+1,n+1) = T(n,0). - Reinhard Zumkeller, Nov 20 2015

Extensions

Corrected and extended by Michel Marcus, Apr 06 2015