A335594 a(n) is the first prime to start a sequence of exactly n primes under the iteration p -> p + (p^2-1)/12.

2, 7, 5, 59, 1657459

Offset

1,1

Comments

No further terms up to 10^8.

Links

Table of n, a(n) for n=1..5.

Example

a(3) = 5 because 5 starts a sequence of exactly 3 primes: 5 -> 5+(5^2-1)/12 = 7 -> 7+(7^2-1)/12 = 11, while 11 + (11^2-1)/12 = 21 is not prime, and 5 is the first prime to do so.

Maple

g:= p -> p + (p^2-1)/12:
f:= proc(p)
    if not isprime(p) then 0
    else 1 + procname(g(p))
    fi
end proc:
A:= Vector(5): A[1]:= 2: count:= 1:
p:= 3:
while count < 5 do
p:= nextprime(p);
v:= f(p);
if A[v] = 0 then count:= count+1; A[v]:= p; fi
od:
convert(A, list);

Crossrefs

Sequence in context: A152555 A343780 A094360 * A051757 A193746 A070524

Adjacent sequences: A335591 A335592 A335593 * A335595 A335596 A335597

Keyword

nonn,more

Author

J. M. Bergot and Robert Israel, Dec 24 2020

Status

approved