1,1

Set R=FLOOR(A(157502)/2), S=FLOOR(SQRT(A(157502))/2), then a(n)=R*(R+1)-(4*S^3+6*S^2+2*S)/3

a(4)=2+6+8+10=26

Sequence in context: A155853 A031061 A125259 this_sequence A137882 A136514 A077071

Adjacent sequences: A157509 A157510 A157511 this_sequence A157513 A157514 A157515

nonn

Gerald Hillier (adr.rabbicat(AT)gmail.com), Mar 02 2009