OFFSET
1,1
EXAMPLE
[5*3-1]/[5-3] = 14/2 = 7
[7*5-1]/[7-5] = 34/2 = 17
[11*7-1]/[11-7] = 76/4 = 19
MAPLE
P:=proc(n) local i, j, k; for i from 1 by 1 to n do j:=(ithprime(i+1)*ithprime(i)-1)/(ithprime(i+1)-ithprime(i)); if j=trunc(j) then if isprime(j) then print(j); fi; fi; od; end: P(1000);
MATHEMATICA
Select[(Times@@#-1)/(#[[2]]-#[[1]])&/@Partition[Prime[Range[200]], 2, 1], PrimeQ]//Sort (* Harvey P. Dale, Jul 29 2024 *)
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Paolo P. Lava and Giorgio Balzarotti, Mar 05 2007
STATUS
approved