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A215284
n such that Sum_{k=1..n} (n - k | k) = 0, where (i|j) is the Kronecker symbol.
4
5, 8, 12, 18, 20, 21, 24, 28, 32, 40, 44, 48, 52, 53, 56, 60, 68, 69, 72, 76, 77, 80, 84, 88, 92, 96, 99, 104, 108, 112, 116, 120, 124, 125, 126, 128, 132, 136, 140, 141, 148, 150, 152, 156, 160, 162, 164, 165, 168, 172, 176, 180, 184, 188, 189, 192, 197
OFFSET
1,1
COMMENTS
Appears to include all multiples of 4 that are not squares. - Robert Israel, Mar 11 2018
LINKS
MAPLE
f:= n -> add(numtheory:-jacobi(n-k, k), k=1..n):
select(n -> f(n)=0, [$1..300]); # Robert Israel, Mar 11 2018
MATHEMATICA
Select[ Range[200], Sum[ KroneckerSymbol[# - k, k], {k, 1, #}] == 0 & ] (* Jean-François Alcover, Jul 29 2013 *)
PROG
(Sage)
def A215200_row(n): return [kronecker_symbol(n-k, k) for k in (1..n)]
[n for n in (1..197) if sum(A215200_row(n)) == 0]
CROSSREFS
KEYWORD
nonn
AUTHOR
Peter Luschny, Aug 07 2012
STATUS
approved