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A239580
Numbers k such that A227364(k) = 1 + 2*3 + 4*5*6 + 7*8*9*10 + ... + ...*k is a prime.
0
2, 3, 4, 6, 9, 10, 13, 14, 15, 18, 30, 32, 54, 58, 59, 81, 85, 128, 140, 203, 204, 206, 209, 223, 286, 305, 343, 350, 367, 397, 399, 451, 453, 506, 534, 656, 676, 698, 730, 756, 845, 849, 878, 944, 1020, 1040, 1091, 1248, 1256, 1300, 1310, 1326, 1364, 1406, 1535
OFFSET
1,1
PROG
(Python)
import sympy
from sympy import isprime
for n in range(10000):
sum = 0
i = k = 1
while i<=n:
product = n
for x in range(k):
product *= i
i += 1
if i>n: break
sum += product
k += 1
if isprime(sum): print str(n)+', ',
CROSSREFS
Cf. A227364.
Sequence in context: A128399 A051404 A046097 * A337724 A175515 A241241
KEYWORD
nonn
AUTHOR
Alex Ratushnyak, Mar 21 2014
STATUS
approved