|
Search: id:A071621
|
|
|
| A071621 |
|
Primes that can be written as "a * b + c * d", where a, b, c and d are also primes. |
|
+0
1
|
|
| 13, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97, 101, 103, 107, 109, 113, 127, 131, 137, 139, 149, 151, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199, 211, 223, 227, 229, 233, 239, 241, 251, 257, 263, 269, 271, 277, 281, 283, 293
(list; graph; listen)
|
|
|
OFFSET
|
1,1
|
|
|
COMMENT
|
As size in the Mathematica coding is increased, the primes not previously covered will probably be forthcoming. Conjecture: Only the primes 2, 3, 5, 7, 11 and 17 are not representable by this form.
|
|
EXAMPLE
|
13 = 2*2+3*3, so 13 belongs to the sequence.
|
|
MATHEMATICA
|
size = 15; Select[ Union[ Flatten[ Table[ ppp = Prime[i]Prime[j] + Prime[k]Prime[l]; If[ PrimeQ[ppp], Print[{Prime[i], Prime[j], Prime[k], Prime[l], ppp}]]; ppp, {i, size}, {j, size}, {k, size}, {l, size} ]]], PrimeQ]
|
|
CROSSREFS
|
Sequence in context: A050717 A088184 A054986 this_sequence A038888 A113017 A007627
Adjacent sequences: A071618 A071619 A071620 this_sequence A071622 A071623 A071624
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
Arnoud Buzing (arnoudb(AT)wolfram.com), Jun 21 2002
|
|
EXTENSIONS
|
Edited by Robert G. WIlson v (rgwv(AT)rgwv.com), Jun 25 2002
|
|
|
Search completed in 0.002 seconds
|
