A160401 Table read by antidiagonals: a(m,n) = the smallest composite multiple of both m and n.

4, 4, 4, 6, 4, 6, 4, 6, 6, 4, 10, 4, 6, 4, 10, 6, 10, 12, 12, 10, 6, 14, 6, 15, 4, 15, 6, 14, 8, 14, 6, 20, 20, 6, 14, 8, 9, 8, 21, 12, 10, 12, 21, 8, 9, 10, 18, 24, 28, 30, 30, 28, 24, 18, 10, 22, 10, 9, 8, 35, 6, 35, 8, 9, 10, 22, 12, 22, 30, 36, 40, 42, 42, 40, 36, 30, 22, 12, 26, 12, 33

Offset: 1

Author

Leroy Quet, May 12 2009

Keywords

• nonn
• tabl

Comments

a(p,1) = a(1,p) = a(p,p) = 2p, where p = any one prime. a(1,1) = 4. Otherwise, a(m,n) = lcm(m,n).

Examples

			Array begins:
   4,  4,  6,  4, 10,  6, ...
   4,  4,  6,  4, 10,  6, ...
   6,  6,  6, 12, 15,  6, ...
   4,  4, 12,  4, 20, 12, ...
  10, 10, 15, 20, 10, 30, ...
   6,  6,  6, 12, 30,  6, ...
  ...
		

Crossrefs

Cf. A003990.

Programs

PARI

T(n, k) = {my(j = lcm(n, k), c = j); while (isprime(c) || (c==1), c += j); c;}
tabl(nn) = for (n=1, nn, for (k=1, nn, print1(T(n, k), ", ")); print); \\ Michel Marcus, Mar 13 2018

Extensions

Extended by Ray Chandler, Jun 18 2009