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A073060
Multiplication table for 1 and odd primes, read by antidiagonals.
0
1, 3, 3, 5, 9, 5, 7, 15, 15, 7, 11, 21, 25, 21, 11, 13, 33, 35, 35, 33, 13, 17, 39, 55, 49, 55, 39, 17, 19, 51, 65, 77, 77, 65, 51, 19, 23, 57, 85, 91, 121, 91, 85, 57, 23, 29, 69, 95, 119, 143, 143, 119, 95, 69, 29, 31, 87, 115, 133, 187, 169, 187, 133, 115, 87, 31, 37, 93, 145
OFFSET
0,2
COMMENTS
Entries in table are sometimes called semiprimes or biprimes (see A001358).
EXAMPLE
Table begins
1 3 5 7 11 13 ...
3 9 15 21 33 ...
5 15 25 35 ...
MAPLE
a[1] := 1:for j from 2 to 100 do a[j] := ithprime(j):od:s := 0:for j from 1 to 16 do for i from 1 to j do s := s+1:b[s] := a[j-i+1]*a[i]; od:od:seq(b[q], q=1..s);
CROSSREFS
Sequence in context: A293676 A303714 A098353 * A183526 A337562 A087343
KEYWORD
nonn,tabl,easy
AUTHOR
Stuart M. Ellerstein (ellerstein(AT)aol.com), Aug 16 2002
EXTENSIONS
Corrected and extended by Sascha Kurz, Jan 28 2003
STATUS
approved