(Product of twin primes - 1)/2.

Terms

a(0) =7a(1) =17a(2) =71a(3) =161a(4) =449a(5) =881a(6) =1799a(7) =2591a(8) =5201a(9) =5831a(10) =9521a(11) =11249a(12) =16199a(13) =18431a(14) =19601a(15) =25991a(16) =28799a(17) =36449a(18) =39761a(19) =48671a(20) =60551a(21) =88199a(22) =93311a(23) =106721a(24) =136241a(25) =162449a(26) =179999a(27) =190961a(28) =206081a(29) =217799