login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 59th year, we have over 358,000 sequences, and we’ve crossed 10,300 citations (which often say “discovered thanks to the OEIS”).

Other ways to Give
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
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. 2
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 (list; table; graph; refs; listen; history; text; internal format)
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 A267077

Adjacent sequences: A174024 A174025 A174026 * A174028 A174029 A174030

KEYWORD

nonn,tabl,uned

AUTHOR

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

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified December 3 19:41 EST 2022. Contains 358543 sequences. (Running on oeis4.)