1,2

A137880 = {1,49,225,23409,108241,11282881,52171729,5438325025,...} = Indices corresponding to the perfect squares in 17-gonal numbers A051869(n) = n(15n -13)/2.

Corresponding 17-gonal numbers k^2 are listed in A137878(n) = A051869( a(n)^2 ) = {1,17689,378225,4109707449,87870152041,954775454112481,20414169462254569,221815343046210267025,...}.

a(n) = Sqrt[ A137880(n) ]. A051869( a(n)^2 ) = A137878(n).

Cf. A051869 = 17-gonal numbers. Cf. A137878 = 17-gonal numbers that are the perfect squares. Cf. A137879, A137880.

Adjacent sequences: A137878 A137879 A137880 this_sequence A137882 A137883 A137884

Sequence in context: A032004 A032018 A068366 this_sequence A042725 A041096 A007541

more,nonn

Alexander Adamchuk (alex(AT)kolmogorov.com), Feb 19 2008