A173865 Alternating triangle read by rows: numbers k such that k=6*m+-1=r*j, r>=j and n>=q where r=6*n-1 or r=6*n+1 and j=6*q-1 or j=6*q+1.

1, 5, 35, 7, 25, 49, 11, 65, 77, 143, 13, 55, 91, 121, 169, 17, 95, 119, 209, 221, 323, 19, 65, 133, 187, 247, 289, 361, 23, 125, 161, 275, 299, 425, 437, 575, 25, 115, 175, 253, 325, 391, 475, 529, 625, 29, 155, 203, 341, 377, 527, 589, 713, 725, 899, 31, 145, 217

Offset

1,2

Comments

Numbers of form 6*m+1 are in even rows, numbers of form 6*m-1 are in odd rows.

Links

Table of n, a(n) for n=1..58.

Example

Triangle begins: 1*1 5*1 7*5 7*1 5*5 7*7 11*1 13*5 11*7 13*11 13*1 11*5 13*7 11*11 13*13 17*1 19*15 17*7 19*11 17*13 19*17 19*1 17*5 19*7 17*11 19*13 17*17 19*19.. or 1(in even 0 row) 5 35(in odd 1 row) 7 25 49(in even 2 row) 11 65 77 143(in odd 3 row) 13 55 91 121 169(in even 4 row) 17 95 119 209 221 323(in odd 5 row) 19 65 133 187 247 289 361(in even 6 row)..

Crossrefs

Cf. A007310, A173825.

Sequence in context: A208098 A216759 A144995 * A285019 A169617 A174130

Adjacent sequences: A173862 A173863 A173864 * A173866 A173867 A173868

Keyword

nonn,tabl

Author

Juri-Stepan Gerasimov, Feb 26 2010, Mar 06 2010

Status

approved