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URL: https://oeis.org/A373181

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A373181
k such that 0 = Sum_{j=1..k} A373223(k, j). The indices of the rows in Gauss's triangle with vanishing row sums.
1
1, 5, 9, 11, 15, 17, 19, 27, 31, 81, 83, 85, 91, 205, 207, 213, 2955, 50299, 50373, 50395, 50397, 50399, 50441, 50453, 50461, 50465, 50505, 50509, 50513, 50519, 50649, 50895, 50897, 50923, 50931, 50933, 50935, 50937, 51117, 51125, 51129, 51131, 51133, 51135, 51165
OFFSET
1,2
COMMENTS
Terms are odd.
The next prime term is 807281. - Michel Marcus, Jun 01 2024
LINKS
MAPLE
select(n -> A373224(n) = 0, [seq(1..300)]);
PROG
(SageMath)
def is_a(n):
p = nth_prime(n)
r = (p - 1)//2
return 0 == sum((-1)^(r*((q - 1)//2)) for q in prime_range(p))
def aList(upto): return [n for n in range(1, upto, 2) if is_a(n)]
print(aList(222))
(PARI) KP(p, q) = kronecker(p, q);
isok(k) = my(vp=primes(k)); vecsum(vector(k, j, KP(vp[k], vp[j])*KP(vp[j], vp[k]))) == 0; \\ Michel Marcus, Jun 01 2024
CROSSREFS
KEYWORD
nonn
AUTHOR
Peter Luschny, May 31 2024
STATUS
approved