A218643 Array, by antidiagonals, A(n,k) = next number that is the product of exactly k primes (not necessarily distinct) after 10*n.

2, 4, 11, 8, 14, 23, 16, 12, 21, 31, 32, 16, 27, 33, 41, 64, 32, 24, 42, 46, 53, 128, 64, 32, 36, 42, 51, 61, 256, 128, 64, 32, 54, 52, 62, 71, 512, 256, 128, 64, 48, 54, 63, 74, 83, 1024, 512, 256, 128, 64, 72, 81, 75, 82, 97, 2048, 1024, 512, 256, 128, 64, 72, 81, 92, 91, 101, 4096, 2048, 1024, 512, 256, 128, 64, 72, 81, 92, 106, 113, 8192, 4096, 2048, 1024, 512, 256, 128, 96, 108, 100, 102, 111, 127

Offset: 1

Author

Jonathan Vos Post, Nov 03 2012

Keywords

• nonn
• easy
• tabl

Examples

			Table begins:
========================================================
...|n=0|n=1|n=2|n=3|n=4|n=5|n=6|n=7|n=7|n=9|n=10|
k=1|.2.|.11|.23|.31|.41|.53|.61|.71|.83|.97|.101|A218255
k=2|.4.|.14|.21|.33|.46|.51|.62|.74|.82|.91|.106|A185008
k=3|.8.|.12|.27|.42|.42|.52|.63|.75|.92|.92|.102|
k=4|16.|.16|.24|.36|.54|.54|.81|.81|.81|100|.104|
k=5|32.|.32|.32|.32|.48|.72|.72|.72|108|108|.108|
k=6|64.|.64|.64|.64|.64|.64|.64|.96|.96|.96|.144|
========================================================
		

Crossrefs

Cf. A008592, A218255, A185008.

Programs

Maple

A218643 := proc(n,k)
    local a;
    for a from 10*n+1 do
        if numtheory[bigomega](a) = k then
            return a;
        end if;
    end do:
end proc:
for d from 1 to 13 do
    for n from 0 to d-1 do
        printf("%d,",A218643(n,d-n)) ;
    end do:
end do: # R. J. Mathar, Nov 07 2012