A143544 - OEIS

%I #11 Nov 01 2021 00:43:26

%S 1,2,2,2,2,2,1,1,1,1,2,2,2,2,2,1,1,1,1,1,1,2,2,2,2,2,2,2,1,1,1,1,1,1,

%T 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,2,2,2,2,2,2,2,2,2,2,2

%N Triangle read by rows, T(n,k) = 2 if n is prime, 1 otherwise; 1<=k<=n.

%C Row sums = A143545: (1, 4, 6, 4, 10, 6, 14,...) = componentwise addition of (1, 2, 3, 4, 5,...) and A061397: (0, 2, 3, 0, 5, 0, 7,...).

%H Michael De Vlieger, <a href="/A143544/b143544.txt">Table of n, a(n) for n = 1..11325</a>

%F Triangle read by rows, T(n,k) = 2 if n is prime, 1 otherwise; 1<=k<=n.

%F T(n, k) = A143536(n, k) + 1. - _Georg Fischer_, Oct 31 2021

%e First few rows of the triangle =

%e 1;

%e 2, 2;

%e 2, 2, 2;

%e 1, 1, 1, 1;

%e 2, 2, 2, 2, 2;

%e 1, 1, 1, 1, 1, 1;

%e 2, 2, 2, 2, 2, 2, 2;

%e ...

%t Table[1 + Boole[PrimeQ[n]], {n, 11}, {k, n}] // Flatten (* _Michael De Vlieger_, Oct 31 2021 *)

%Y Cf. A010051, A061397, A143536, A143545.

%K nonn,tabl

%O 1,2

%A _Gary W. Adamson_, Aug 23 2008