OFFSET
1,6
REFERENCES
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
LINKS
Robin Visser, Table of n, a(n) for n = 1..10000
D. Shanks, The simplest cubic fields, Math. Comp., 28 (1974), 1137-1152 (see Table 2 page 1143).
PROG
(Sage)
def a(n):
m, k = 1, 1
while (m < n): k += 1; m += (k^2+4).is_prime()
return QuadraticField(k^2+4).class_number() # Robin Visser, Dec 07 2024
CROSSREFS
KEYWORD
nonn
AUTHOR
EXTENSIONS
More terms and name edited by Robin Visser, Dec 07 2024
STATUS
approved