The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A344886 (Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
Showing entries 1-10 | older changes

A344886

a(n) is the smallest triangular number that is a multiple of the product of the members of the n-th pair of twin primes.
(history; published version)

#44 by N. J. A. Sloane at Tue Jul 06 02:58:52 EDT 2021

STATUS

editing

approved

#43 by N. J. A. Sloane at Tue Jul 06 02:58:48 EDT 2021

NAME

a(n) is the least smallest triangular number that is a multiple of the product of the members of the n-th pair of twin primes.

COMMENTS

This is a subsequence of A011772, which is really the basic sequence here. - N. J. A. Sloane, Jul 06 2021

CROSSREFS

See also A011772.

STATUS

proposed

editing

#42 by Ali Sada at Thu Jun 17 14:34:44 EDT 2021

STATUS

editing

proposed

#41 by Michel Marcus at Thu Jun 10 05:59:21 EDT 2021

STATUS

proposed

editing

Discussion

Thu Jun 17

10:08

OEIS Server: This sequence has not been edited or commented on for a week
yet is not proposed for review.  If it is ready for review, please
visit https://oeis.org/draft/A344886 and click the button that reads
"These changes are ready for review by an OEIS Editor."

Thanks.
  - The OEIS Server

#40 by Michel Marcus at Thu Jun 10 05:42:07 EDT 2021

STATUS

editing

proposed

Discussion

Thu Jun 10

05:59

Ali Sada: 3*A001359(2)*A308344(2)*A006512(1)=3*5*7*1=105

#39 by Michel Marcus at Thu Jun 10 05:41:46 EDT 2021

PROG

(PARI) a001359(n, p=3) = { while( p+2 < (p=nextprime( p+1 )) || n-->0, ); p-2};

a(n) = my(p=a001359(n), k = (p-1)*(p+2)/2); k*(k+1)/2; \\ Michel Marcus, Jun 10 2021

STATUS

proposed

editing

Discussion

Thu Jun 10

05:42

Michel Marcus: pari program after Jon formula

#38 by Ali Sada at Thu Jun 10 05:24:39 EDT 2021

STATUS

editing

proposed

Discussion

Thu Jun 10

05:38

Michel Marcus: for me, the formula still does not work : For n=2, a(2) = 3*A001359(2)*A308344(2)*A006512(1) = 3*5*5*5 = 375

#37 by Ali Sada at Thu Jun 10 05:24:03 EDT 2021

FORMULA

For n > 1 a(n) = 3*A001359(n)*A308344(n)*A006512(n-1)*A308344(n).

Discussion

Thu Jun 10

05:24

Ali Sada: Corrected it

#36 by Ali Sada at Thu Jun 10 05:22:07 EDT 2021

FORMULA

For n > 1 a(n) = 3*A001359(n)*A006512(n-1)*A308344(n).

STATUS

proposed

editing

#35 by Felix Fröhlich at Wed Jun 09 14:58:05 EDT 2021

STATUS

editing

proposed

Discussion

Thu Jun 10

03:07

Michel Marcus: the formula a(n) = 3*A001359(n)*A006512(n)*A308344(n). does not seem right : example for n=1; a(1) = 3*3*5*1 = 45 instead of 15

04:45

Hugo Pfoertner: The sequence terms are consistent with the definition in the name. I've checked them  with a simple PARI program. The questionable formula does not come from me, but Ali quoted my name, although I was not responsible for it.

05:07

Hugo Pfoertner: In the case of sequences dealing with twin primes, it usually makes sense to exclude the irregular pair (3,5) and start with (5,7). (3,5) breaks many otherwise valid relationships.