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 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. 2
 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 (list; table; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 LINKS Reinhard Zumkeller, Rows n = 0..120 of triangle, flattened 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 EXAMPLE Triangle begins 1; 2, 1; 6, 3, 2; 30, 15, 10, 6; 210, 105, 70, 42, 30; PROG (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 (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 CROSSREFS Cf. A000040, A002110, A024528, A070826. Sequence in context: A097905 A094310 A165908 * A232467 A131449 A289869 Adjacent sequences:  A121278 A121279 A121280 * A121282 A121283 A121284 KEYWORD nonn,tabl AUTHOR Philippe Deléham, Aug 24 2006 EXTENSIONS Corrected and extended by Michel Marcus, Apr 06 2015 STATUS approved

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Last modified January 23 15:15 EST 2021. Contains 340385 sequences. (Running on oeis4.)