A087901 Twin primes associated with A087900.
5, 7, 29, 31, 179, 181, 1619, 1621, 21059, 21061, 463319, 463321, 11119679, 11119681, 567103679, 567103681, 52173538559, 52173538561, 6260824627199, 6260824627201, 1101905134387199, 1101905134387201, 284291524671897599, 284291524671897601, 77895877760099942399, 77895877760099942401
Offset: 1
Links
- Robert Israel, Table of n, a(n) for n = 1..418
Crossrefs
Cf. A087900.
Programs
-
Maple
R:= NULL; s:= 2: count:= 0: for r from 3 while count < 30 do if isprime(s*r+1) and isprime(s*r-1) then count:= count+2; s:= s*r; R:= R,s-1,s+1; fi; od: R; # Robert Israel, Jun 11 2025
Formula
From Robert Israel, Jun 11 2025: (Start)
a(2*n-1) = (Product_{i=1..n+1} A087900(i)) - 1.
a(2*n) = (Product_{i=1..n+1} A087900(i)) + 1. (End)