A140755 - OEIS

%I #17 Oct 22 2023 16:55:04

%S 43,47,53,61,71,83,97,113,131,151,173,197,223,251,281,313,347,383,421,

%T 461,167,172,179,188,199,212,227,244,263,284,307,332,359,388,419,452,

%U 487,524,563,604,373,379,387,397,409,423,439

%N Square array read by rows: T(n,k) = 41*n^2 + k^2 + n*k, with 20 columns.

%C The original definition of this sequence was obscure: "A prime array is embedded in a binary quadratic equation that is a transform of x^2 - x + 41".

%H G. C. Greubel, <a href="/A140755/b140755.txt">Table of n, a(n) for n = 1..400</a>

%t With[{m=20}, Table[41*n^2 +k^2 +n*k, {n,m}, {k,m}]//Flatten (* _G. C. Greubel_, Oct 21 2023 *)

%o (Magma) m:=20; [41*n^2 +k^2 +n*k: k in [1..m], n in [1..m]]; // _G. C. Greubel_, Oct 21 2023

%o (SageMath) flatten([[41*n^2+k^2+n*k for k in range(1,21)] for n in range(1,21)]) # _G. C. Greubel_, Oct 21 2023

%Y Cf. A140340, A140754 (very similar arrays).

%K nonn,tabf,easy,less

%O 1,1

%A Aldrich Stevens (aldrichstevens(AT)msn.com), May 27 2008

%E Partially edited with better definition by _Omar E. Pol_, Jan 11 2009

%E More terms from _Omar E. Pol_, Jan 11 2009