A384875 Irregular triangle T(n,k) = 2^(floor(n/3)-k) * nextprime(2^(n-2*(floor(n/3)-k))), with k = 0..floor(n/3)-1.
6, 10, 22, 20, 34, 44, 74, 68, 134, 88, 148, 262, 136, 268, 514, 296, 524, 1042, 272, 536, 1028, 2062, 592, 1048, 2084, 4106, 1072, 2056, 4124, 8198, 1184, 2096, 4168, 8212, 16418, 2144, 4112, 8248, 16396, 32822, 4192, 8336, 16424, 32836, 65542, 4288, 8224, 16496, 32792, 65644, 131074
Offset: 3
Examples
Table begins: n\k 0 1 2 3 4 --------------------------------------- 3: 6 4: 10 5: 22 6: 20 34 7: 44 74 8: 68 134 9: 88 148 262 10: 136 268 514 11: 296 524 1042 12: 272 536 1028 2062 13: 592 1048 2084 4106 14: 1072 2056 4124 8198 15: 1184 2096 4168 8212 16418 ... Let S = A010846. Tables showing terms in row a(n) of A162306, listed in order of row a(n) of A275280. T(3,1) = 6, S(6) = 5: 1 2 4 3 6 T(4,1) = 10, S(10) = 6: 1 2 4 8 5 10 T(5,1) = 22, S(22) = 7: 1 2 4 8 16 11 22 T(6,1) = 20, T(6,2) = 34, S(20) = 8: S(34) = 8: 1 2 4 8 16 1 2 4 8 16 32 5 10 20 17 34 T(7,1) = 44, T(7,2) = 74, S(44) = 9: S(74) = 9: 1 2 4 8 16 32 1 2 4 8 16 32 64 11 22 44 37 74 T(8,1) = 68, T(8,2) = 134, S(68) = 10: S(134) = 10: 1 2 4 8 16 32 64 1 2 4 8 ... 128 17 34 68 67 134 T(9,1) = 88, T(9,2) = 148, T(9,3) = 262, S(88) = 11: S(148) = 11: S(262) = 11: 1 2 4 8 16 32 64 1 2 4 8 ... 128 1 2 ... 256 11 22 44 88 37 74 148 131 262 etc.
Links
- Michael De Vlieger, Table of n, a(n) for n = 3..10377 (rows n = 3..250, flattened).
- Michael De Vlieger, Log log scatterplot showing the first 2380 terms.
Programs
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Mathematica
Table[2^k*NextPrime[2^(n - 2*k)], {n, 3, 18}, {k, Floor[n/3], 1, -1}] // TableForm
Formula
A010846(T(n,k)) = n+2.