1,2

Given A086606={1,_1,2,_1,3,9,_1,4,14,32,_1,5,20,55,140, ...},

a(2)=3=1+2 since A086606^2={1,2, ...},

a(3)=13=1+3+9 since A086606^3={1,3,9, ...},

a(4)=51=1+4+14+32 since A086606^4={1,4,14,32, ...},

a(5)=221=1+5+20+55+140 since A086606^5={1,5,20,55,140, ...}.

Cf. A086606 (triangle), A086607 (diagonal).

Sequence in context: A015521 A146279 A098619 this_sequence A037772 A037660 A122600

Adjacent sequences: A086605 A086606 A086607 this_sequence A086609 A086610 A086611

nonn

Paul D. Hanna (pauldhanna(AT)juno.com), Jul 23 2003