1,1

Least number k such that A001157(k) is the sum of two nonzero squares in exactly n ways.

a(17), if it exists, is > 10^7. Additional terms for n > 16: ?, 2914, ?, 2456, 21490, 18330, 13160, 4216, 40152, ?, 11656, 17192, ?, 12280, 156570, 9734, 4306794, ?, 431634, 17954, 411558, 173992, ?, 22922, 77080, 85960... - Lars Blomberg, Sep 20 2017

Table of n, a(n) for n=1..16.

a(2) = 6 because 6 is divisible by 1, 2, 3, 6. 1^2 + 2^2 + 3^2 + 6^2 = 1^2 + 7^2 = 5^2 + 5^2.

Cf. A001157, A016032.

Sequence in context: A137326 A163912 A257546 * A143383 A067653 A090755

Adjacent sequences: A274035 A274036 A274037 * A274039 A274040 A274041

nonn,more

Altug Alkan, Jun 13 2016

a(11) from Giovanni Resta, Jun 13 2016

a(14)-a(16) from Lars Blomberg, Sep 20 2017

approved