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

1,1

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).

Links

Table of n, a(n) for n=1..81.

Example

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, ...
  ...

Prog

(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

Crossrefs

Cf. A003990.

Sequence in context: A130331 A141241 A140696 * A114742 A273909 A098013

Adjacent sequences: A160398 A160399 A160400 * A160402 A160403 A160404

Keyword

nonn,tabl

Author

Leroy Quet, May 12 2009

Extensions

Extended by Ray Chandler, Jun 18 2009

Status

approved