A249545 a(n) = number of representations of A020670(n) as x^2 + 7*y^2.

1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 3, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 2, 1, 1, 2, 1, 3, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 3, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 2, 1, 1, 1, 2, 4, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 2, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 2, 1, 4, 1, 1, 3, 1, 1, 1, 1

Offset: 1

Author

Zak Seidov, Oct 31 2014

Keywords

• nonn

Comments

Among first 10000 terms, maximal value is 12 for n = 5875, 7320, 9211.

That is, numbers A020670(5875, 7320, 9211) = (32384, 40832, 52096) are expressible as x^2 + 7*y^2 in 12 ways. E.g., 32384 = x^2 + 7*y^2 for {x,y}= {4, 68}, {31, 67}, {53, 65}, {74, 62}, {94, 58}, {116, 52}, {122, 50}, {151, 37}, {164, 28}, {172, 20}, {178, 10}, {179, 7}.

Links

• Zak Seidov, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A020670.