A106727 - OEIS

%I #23 Sep 11 2021 15:12:14

%S 9,7,1,1,3,9,9,7,1,9,3,9,7,3,1,1,3,9,1,7,9,3,9,7,3,1,7,1,7,1,3,7,9,3,

%T 9,1,9,7,1,9,3,1,3,7,9,7,1,3,7,9,3,9,1,7,1,1,3,9,1,7,9,7,3,1,3,9,9,7,

%U 1,9,3,1,3,7,9,7,1,9,1,3,9,1,7,9,7,3,1,3,9,1,9

%N Triangle T(n,k) = (f(n+1)*f(k+1) mod 10), where f(j) = 10 - (prime(j+3) mod 10), read by rows.

%H G. C. Greubel, <a href="/A106727/b106727.txt">Rows n = 0..50 of the triangle, flattened</a>

%F T(n, k) = (f(n+1)*f(k+1) mod 10) where f(j) = 10 - (prime(j+3) mod 10).

%e Triangle begins:

%e   9;

%e   7, 1;

%e   1, 3, 9;

%e   9, 7, 1, 9;

%e   3, 9, 7, 3, 1;

%e   1, 3, 9, 1, 7, 9;

%e   3, 9, 7, 3, 1, 7, 1;

%t f[n_]:= 10 - Mod[Prime[n+3], 10];

%t Table[Mod[f[n+1]*f[k+1], 10], {n,0,15}, {k,0,n}]//Flatten

%o (Sage)

%o def f(n): return 10 - (nth_prime(n+3)%10)

%o def A106727(n,k): return (f(n+1)*f(k+1))%10

%o flatten([[A106727(n,k) for k in (0..n)] for n in (0..15)]) # _G. C. Greubel_, Sep 10 2021

%Y Cf. A007652, A072003.

%K nonn,easy,base,less,tabl

%O 0,1

%A _Roger L. Bagula_, May 14 2005