OFFSET
1,1
EXAMPLE
97 is a term because up to the next prime 101, tau(98) = 6, tau(99) = 6, tau(100) = 9, thus the greatest tau is 9 and 9 is a square (3^2).
127 is prime but not a term because up to the next prime 131, tau(128) = 8, tau(129) = 4, tau(130) = 8, thus the greatest tau(k) is 8 and 8 is not a square.
MATHEMATICA
Select[Prime[Range[2, 220]], IntegerQ[Sqrt[Max[DivisorSigma[0, Range[# + 1, NextPrime[#] - 1]]]]] &] (* Amiram Eldar, Jun 10 2022 *)
PROG
(PARI) forprime(p=3, 2000, my(v=vector(nextprime(p+1)-p-1, k, numdiv(p+k))); if(ispower(vecmax(v), 2), print1(p", ")))
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Claude H. R. Dequatre, Apr 09 2022
STATUS
approved