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 A160401 Table read by antidiagonals: a(m,n) = the smallest composite multiple of both m and n. 0
 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 (list; table; graph; refs; listen; history; text; internal format)
 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 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,changed AUTHOR Leroy Quet, May 12 2009 EXTENSIONS Extended by Ray Chandler, Jun 18 2009 STATUS approved

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Last modified March 22 05:43 EDT 2018. Contains 301047 sequences. (Running on oeis4.)