OFFSET
1,1
COMMENTS
Sum_{n>=1} 1/a(n) = 0.538046187...
LINKS
Chai Wah Wu, Table of n, a(n) for n = 1..5231
FORMULA
PROG
(Python)
def prime(n):
if n == 1: return True
d = n + 1
c = n - 1
while c > 0 and d % c:
d += n
c -= 1
return bool(c == 1)
n = 1
i = 1
while i <= 500:
target = (i * (i + 1)) // 2
if prime(target):
print(n, target*target+1)
n += 1
i += 1
# Jean C. Lambry, Oct 06 2015
(PARI) for(n=1, 1e3, if(isprime(k = (n*(n+1)/2)^2+1), print1(k", "))) \\ Altug Alkan, Oct 02 2015
CROSSREFS
KEYWORD
nonn
AUTHOR
Jean C. Lambry, Oct 02 2015
EXTENSIONS
More terms from Altug Alkan, Oct 02 2015
STATUS
approved