a(n) is the smallest even number not congruent to 1 modulo 3 that starts a (2n+1)-element alternating sequence of x/2 and (3x+1) iterations ending in the maximum of its Collatz trajectory.

A277215

a(n) is the smallest even number not congruent to 1 modulo 3 that starts a (2n+1)-element alternating sequence of x/2 and (3x+1) iterations ending in the maximum of its Collatz trajectory.

Terms

    a(0) =0a(1) =26a(2) =6a(3) =14a(4) =30a(5) =1214a(6) =1662a(7) =254a(8) =510a(9) =1022a(10) =2046a(11) =28670a(12) =40958a(13) =180222a(14) =32766a(15) =65534a(16) =131070a(17) =1835006a(18) =5767166a(19) =1048574a(20) =2097150a(21) =4194302a(22) =8388606a(23) =16777214a(24) =33554430a(25) =469762046a(26) =671088638a(27) =268435454a(28) =536870910a(29) =7516192766

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