A174027 Alternating triangle (version 2) read by rows: composites k such that k=6*m-+1=r*j r>=j and n>=q>0 where r=6*n-1 or r=6*n+1 and j=6*q-1 or j=6*q+1.

35, 25, 49, 65, 77, 143, 55, 91, 121, 169, 95, 119, 209, 221, 323, 65, 133, 187, 247, 289, 361, 125, 161, 275, 299, 425, 437, 575, 115, 175, 253, 325, 391, 475, 529, 625, 155, 203, 341, 377, 527, 589, 713, 725, 899, 145, 217, 319, 403, 493, 569, 667, 775, 841

Offset

1,1

Comments

Composites of form 6*m-1 are in even (0,2,4,..) rows of alternating triangle only. Composites of form 6*m+1 are in odd (1,3,5,..) rows of alternating triangle only. 1 UNION nontrivial primes UNION A174027(without repetition) = A140475 U A174027(without repetition) = A007310 = numbers of form 6*n+-1, where alternating triangle (version 1) is A173865.

Links

Table of n, a(n) for n=1..54.

Example

Triangle begins:
35(=7*5) in even 0th row;
25(=5*5) and 49(=7*7) in odd 1st row;
65(=13*5), 77(=11*7) and 143(=13*11) in even 2nd row.

Crossrefs

Cf. A007310, A140475, A173825, A173865.

Sequence in context: A217408 A266057 A267341 * A259083 A244214 A358931

Adjacent sequences: A174024 A174025 A174026 * A174028 A174029 A174030

Keyword

nonn,tabl,uned

Author

Juri-Stepan Gerasimov, Mar 06 2010, Mar 17 2010

Status

approved