A127257 -id:A127257 - cp's OEIS frontend

A127256 a(n) is the initial element of the sequence A(n) defined exactly like A119751 but with the additional condition that each of its elements must not be contained in any of the sequences A(k) for k < n.

1, 5, 15, 23, 33, 41, 53, 75, 89, 99, 105, 113, 153, 155, 165, 189, 215, 239, 249, 261, 281, 293, 323, 341, 363, 371, 375, 405, 411, 419, 431, 473, 519, 543, 545, 561, 575, 629, 659, 699, 725, 741, 743, 765, 785, 803, 831, 849, 893, 905, 915, 923, 933, 935

Offset: 1

Walter Kehowski, Jan 10 2007

nonn

a(n)=A(n,1), the first element of each sequence A(n) defined recursively as follows. Recall that A119751 is the sequence defined recursively by a(1)=1 and a(k) is the first odd number greater than a(k-1) such that 2a(k)+1 is prime and a(k)+a(j)+1 is prime for all 1<=jA119751, that is, A(1,k)=A119751(k). Then A(n) is the sequence defined recursively as follows: (1) A(n,1) is the first odd number not in any A(m), 1<=m

			a(1)=1 is the first element of A119751=1, 3, 9, 69, 429, 4089, 86529, 513099, ... so a(2)=5 since 5 is the first odd number not in A119751 such that 2*5+1 is prime. Furthermore, A(2)=5, 11, 35, 95, 221, 551, 1271, 5705,...

Cf. A119751, A119752, A127257.

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A127256 a(n) is the initial element of the sequence A(n) defined exactly like A119751 but with the additional condition that each of its elements must not be contained in any of the sequences A(k) for k < n.

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