A106727 Triangle T(n,k) = (f(n+1)*f(k+1) mod 10), where f(j) = 10 - (prime(j+3) mod 10), read by rows.

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, 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, 1, 9, 3, 1, 3, 7, 9, 7, 1, 9, 1, 3, 9, 1, 7, 9, 7, 3, 1, 3, 9, 1, 9

Offset: 0

Author

Roger L. Bagula, May 14 2005

Keywords

• nonn
• easy
• base
• less
• tabl

Examples

			Triangle begins:
  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;
		

Links

• G. C. Greubel, Rows n = 0..50 of the triangle, flattened

Crossrefs

Cf. A007652, A072003.

Programs

Mathematica

f[n_]:= 10 - Mod[Prime[n+3], 10];
Table[Mod[f[n+1]*f[k+1], 10], {n,0,15}, {k,0,n}]//Flatten

Sage

def f(n): return 10 - (nth_prime(n+3)%10)
def A106727(n,k): return (f(n+1)*f(k+1))%10
flatten([[A106727(n,k) for k in (0..n)] for n in (0..15)]) # G. C. Greubel, Sep 10 2021

Formula

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