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A262436
Number of ways to represent 2n - 1 as p^2 + q^2 + r with p, q, and r prime, and p >= q.
1
0, 0, 0, 0, 0, 1, 1, 2, 0, 1, 2, 1, 2, 1, 1, 3, 0, 1, 3, 2, 2, 0, 2, 2, 2, 2, 2, 4, 2, 1, 4, 3, 3, 2, 3, 3, 1, 3, 4, 4, 5, 0, 2, 5, 2, 4, 3, 2, 4, 1, 4, 3, 5, 2, 3, 5, 1, 4, 6, 2, 5, 2, 2, 4, 3, 3, 3, 5, 3, 3, 5, 2, 4, 6, 3, 3, 4, 2, 6, 6, 3, 3, 5, 3, 3, 6, 3
OFFSET
1,8
COMMENTS
k is in A212292 if and only if a((k+1)/2) = 0.
FORMULA
a(16) = 3 because there are three different ways to represent 16 * 2 - 1 = 31 in the form p^2 + q^2 + r with p, q, and r prime, and p >= q:
2^2 + 2^2 + 23,
3^3 + 3^3 + 13,
5^2 + 2^2 + 2.
CROSSREFS
Cf. A212292.
Sequence in context: A274659 A274661 A225089 * A336499 A093998 A247918
KEYWORD
nonn
AUTHOR
Peter Kagey, Sep 22 2015
STATUS
approved