Metadata
bibkey: librandi2012a140869
authors: Vincenzo Librandi
year: 2012
title: "OEIS A140869, Triangle read by rows where T(m,n) = floor((2mn+m+n-2)/2), m >= n >= 1"
doi: null
url: https://oeis.org/A140869
claim: "A140869 %N: T(m,n) = floor((2mn+m+n-2)/2), m >= n >= 1. A140869 %C: Conjecture: If h does not belong to the sequence, then 4*h+5 is prime. - _Vincenzo Librandi_, Nov 18 2012. A140869 %A: _Vincenzo Librandi_, Jan 16 2009"
strata_touched:
- D5/S3/Arith/Congruence/LibrandiSundaramTriangleComplementPrime
license: citation-only
triage: anchor
OEIS A140869
The entry defines the rows by
T(m,n) = floor((2mn+m+n-2)/2) for m >= n >= 1 and records the conjecture
that a value outside the sequence gives a prime 4*h+5.
Verified locator
- URL: https://oeis.org/A140869
- Locator: COMMENTS, “Conjecture: If h does not belong to the sequence, then 4*h+5 is prime. - Vincenzo Librandi, Nov 18 2012”
The parametrization is of Sundaram’s sieve type, using the numbers i + j + 2ij
described in 1934; that historical observation is context, not a proof of this statement.