a(0)=0; thereafter a(n) = a(n-1)+n if the (n-1)st digit of the sequence is even, otherwise a(n) = a(n-1)-n.

A309216

a(0)=0; thereafter a(n) = a(n-1)+n if the (n-1)st digit of the sequence is even, otherwise a(n) = a(n-1)-n.

Terms

    a(0) =0a(1) =1a(2) =-1a(3) =-4a(4) =0a(5) =5a(6) =-1a(7) =-8a(8) =0a(9) =9a(10) =-1a(11) =-12a(12) =-24a(13) =-11a(14) =3a(15) =18a(16) =2a(17) =-15a(18) =-33a(19) =-52a(20) =-32a(21) =-11a(22) =-33a(23) =-56a(24) =-80a(25) =-105a(26) =-131a(27) =-104a(28) =-132a(29) =-103

External references