1+4=5,2+5=12,3+6=21, 8+11=
1 + 4 = 5;2 + 5 = 12 (i.e. 5 + 7 );3 + 6 = 21(i.e. 12 + 9 );4 + 7 = 32(i.e. 21 + 11 );5 + 8 = 45(i.e. 32 + 13 );6 + 9 = 60(i.e. 45 + 15 );7 + 10 = 77(i.e. 60 + 17 );8 + 11 = 96(i.e. 77 + 19 ).