login
A237992
Numbers which can be decomposed as pq + qr + rp (where p < q < r are distinct primes) in more ways than any smaller number.
1
31, 71, 151, 191, 311, 1031, 1991, 3191, 5351, 5591, 10391, 15791, 17111, 27191, 31391, 35591, 42311, 50951, 70391, 93551, 107159, 117911, 119831, 126551, 166871, 180311, 191831, 216191, 255191, 259871, 327071, 366791, 435431, 465911, 514751, 576551, 599231, 631991
OFFSET
1,1
COMMENTS
Records in A238403.
EXAMPLE
71 = 3*5 + 3*7 + 5*7 = 2*3 + 2*13 + 3*13 can be written in two ways, while smaller numbers can be written in at most one way.
PROG
(PARI) do(n)=my(v=vectorsmall(n), r); forprime(r=5, (n-6)\5, forprime(q=3, min((n-2*r)\(r+2), r-2), my(S=q+r, P=q*r); forprime(p=2, min((n-P)\S, q-1), v[p*S+P]++))); for(i=1, #v, if(v[i]>r, r=v[i]; print1(i", "))
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved