This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A384875 #22 Jul 06 2025 10:01:56
%S A384875 6,10,22,20,34,44,74,68,134,88,148,262,136,268,514,296,524,1042,272,
%T A384875 536,1028,2062,592,1048,2084,4106,1072,2056,4124,8198,1184,2096,4168,
%U A384875 8212,16418,2144,4112,8248,16396,32822,4192,8336,16424,32836,65542,4288,8224,16496,32792,65644,131074
%N 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.
%H A384875 Michael De Vlieger, <a href="/A384875/b384875.txt">Table of n, a(n) for n = 3..10377</a> (rows n = 3..250, flattened).
%H A384875 Michael De Vlieger, <a href="/A384875/a384875.png">Log log scatterplot</a> showing the first 2380 terms.
%F A384875 A010846(T(n,k)) = n+2.
%e A384875 Table begins:
%e A384875 n\k 0 1 2 3 4
%e A384875 ---------------------------------------
%e A384875 3: 6
%e A384875 4: 10
%e A384875 5: 22
%e A384875 6: 20 34
%e A384875 7: 44 74
%e A384875 8: 68 134
%e A384875 9: 88 148 262
%e A384875 10: 136 268 514
%e A384875 11: 296 524 1042
%e A384875 12: 272 536 1028 2062
%e A384875 13: 592 1048 2084 4106
%e A384875 14: 1072 2056 4124 8198
%e A384875 15: 1184 2096 4168 8212 16418
%e A384875 ...
%e A384875 Let S = A010846.
%e A384875 Tables showing terms in row a(n) of A162306, listed in order of row a(n) of A275280.
%e A384875 T(3,1) = 6,
%e A384875 S(6) = 5:
%e A384875 1 2 4
%e A384875 3 6
%e A384875 T(4,1) = 10,
%e A384875 S(10) = 6:
%e A384875 1 2 4 8
%e A384875 5 10
%e A384875 T(5,1) = 22,
%e A384875 S(22) = 7:
%e A384875 1 2 4 8 16
%e A384875 11 22
%e A384875 T(6,1) = 20, T(6,2) = 34,
%e A384875 S(20) = 8: S(34) = 8:
%e A384875 1 2 4 8 16 1 2 4 8 16 32
%e A384875 5 10 20 17 34
%e A384875 T(7,1) = 44, T(7,2) = 74,
%e A384875 S(44) = 9: S(74) = 9:
%e A384875 1 2 4 8 16 32 1 2 4 8 16 32 64
%e A384875 11 22 44 37 74
%e A384875 T(8,1) = 68, T(8,2) = 134,
%e A384875 S(68) = 10: S(134) = 10:
%e A384875 1 2 4 8 16 32 64 1 2 4 8 ... 128
%e A384875 17 34 68 67 134
%e A384875 T(9,1) = 88, T(9,2) = 148, T(9,3) = 262,
%e A384875 S(88) = 11: S(148) = 11: S(262) = 11:
%e A384875 1 2 4 8 16 32 64 1 2 4 8 ... 128 1 2 ... 256
%e A384875 11 22 44 88 37 74 148 131 262
%e A384875 etc.
%t A384875 Table[2^k*NextPrime[2^(n - 2*k)], {n, 3, 18}, {k, Floor[n/3], 1, -1}] // TableForm
%Y A384875 Cf. A006881, A010846, A100484.
%K A384875 nonn,tabf,easy
%O A384875 3,1
%A A384875 _Michael De Vlieger_, Jun 11 2025