Numbers not of form abc + abd + acd + bcd for 1<=a<=b<=c<=d.

Terms

a(0) =1a(1) =2a(2) =3a(3) =5a(4) =6a(5) =8a(6) =9a(7) =11a(8) =14a(9) =15a(10) =18a(11) =21a(12) =23a(13) =26a(14) =29a(15) =30a(16) =33a(17) =35a(18) =41a(19) =48a(20) =51a(21) =53a(22) =63a(23) =65a(24) =74a(25) =75a(26) =86a(27) =89a(28) =90a(29) =98