|
|
A119752
|
|
a(1)=2; a(n)=first even number greater than a(n-1) such that a(i)+a(n)+1 is prime for all i=1,2,...,n.
|
|
9
|
|
|
2, 8, 14, 44, 224, 638, 1274, 4004, 675404, 2203958, 3075158, 6195234164, 77989711184, 4566262987328
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,1
|
|
LINKS
|
|
|
MAPLE
|
R:= [2]: count:= 1:
for k from 4 by 2 while count < 11 do
if isprime(2*k+1) and andmap(isprime, [seq(R[i]+k+1, i=1..count)]) then
R:= [op(R), k]; count:= count+1
fi
od:
|
|
MATHEMATICA
|
Table[If[n == 1, a[1] = 2, j = a[n - 1] + 2; While[a[n] = j; !
AllTrue[Table[a[i] + a[n] + 1, {i, 1, n}], PrimeQ], j += 2]; j]
|
|
PROG
|
(PARI) isok(va, k, n) = if (isprime(2*k+1), for (i=1, n-1, if (! isprime(va[i]+k+1), return(0))); return(1));
lista(nn) = my(va=vector(nn)); va[1]=2; for (n=2, nn, my(k=va[n-1]+2); while (!isok(va, k, n), k+=2); va[n] = k); va; \\ Michel Marcus, Mar 06 2023
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn,more,hard
|
|
AUTHOR
|
|
|
EXTENSIONS
|
|
|
STATUS
|
approved
|
|
|
|