1,2

The calculation is tricky because the generating group has an extra ("hexlet") identity.

Starting with five spheres with bends 0,0,1,1,1, the next (second) generation contains five more spheres with bends 1,1,1,3,3. The sum of squares of these bends is 21 = 7*3 so a(2) = 7. The third generation contains 20 spheres with bends 1^6 3^6 4^6 6^2, sumsq = 228 = 3*a(3).

Cf. A139470 gives the number of spheres added in the n-th generation. The corresponding result for the sum of the bends is in A139471. For the corresponding 2-dimensional sequences, see A135849 and A137246.

Sequence in context: A127190 A121316 A066302 this_sequence A114470 A098497 A059195

Adjacent sequences: A139469 A139470 A139471 this_sequence A139473 A139474 A139475

hard,more,nonn

Colin Mallows (colinm(AT)avaya.com), Apr 22 2008