Numbers k such that 1*k + 1, 3*k + 1, 9*k + 1, 27*k + 1 are all primes.

Terms

a(0) =4a(1) =60a(2) =180a(3) =760a(4) =910a(5) =1020a(6) =1230a(7) =1600a(8) =1860a(9) =2160a(10) =2280a(11) =2440a(12) =3850a(13) =5800a(14) =7320a(15) =8680a(16) =12940a(17) =13780a(18) =14740a(19) =17350a(20) =17400a(21) =21840a(22) =22720a(23) =22960a(24) =26040a(25) =27010a(26) =31050a(27) =33870a(28) =34060a(29) =35200