A164381 Triangle T(n,k) read by rows: T(n,k) = 1 if (n mod k) <= 2*k/9, -1 if 2*k/9 < (n mod k) <= 4*k/9, otherwise 0.

1, 1, 1, 1, 0, 1, 1, 1, -1, 1, 1, 0, 0, -1, 1, 1, 1, 1, 0, 1, 1, 1, 0, -1, 0, -1, 1, 1, 1, 1, 0, 1, 0, -1, 1, 1, 1, 0, 1, -1, 0, 0, -1, 1, 1, 1, 1, -1, 0, 1, 0, -1, -1, 1, 1, 1, 0, 0, 0, 1, 0, 0, -1, 1, 1, 1, 1, 1, 1, 1, -1, 1, 0, 0, -1, 1, 1, 1, 1, 0, -1, -1, 0, 1, 0, 0, -1, -1, 1, 1, 1

Offset

0,1

Links

G. C. Greubel, Table of n, a(n) for the first 50 rows, flattened

Example

Triangle begins as:
  1;
  1,  1;
  1,  0,  1;
  1,  1, -1,  1;
  1,  0,  0, -1,  1;
  1,  1,  1,  0,  1,  1;
  1,  0, -1,  0, -1,  1,  1;
  1,  1,  0,  1,  0, -1,  1,  1;
  1,  0,  1, -1,  0,  0, -1,  1,  1;
  1,  1, -1,  0,  1,  0, -1, -1,  1,  1;

Mathematica

T[n_, k_]:= If[Mod[n, k]/k<=2/9, 1, If[2/9<Mod[n, k]/k<=4/9, -1, 0]];
Table[T[n, k], {n, 12}, {k, n}]//Flatten

Prog

(Magma)
function A164381(n, k)
  if (n mod k) le 2*k/9 then return 1;
  elif 2*k/9 lt (n mod k) and (n mod k) le 4*k/9 then return -1;
  else return 0;
  end if; return A164381;
end function;
[A164381(n, k): k in [1..n], n in [1..12]]; // G. C. Greubel, Dec 03 2022
(SageMath)
def A164381(n, k):
    if ((n%k)/k <= 2/9): return 1
    elif (2/9 < (n%k)/k <= 4/9): return -1
    else: return 0
flatten([[A164381(n, k) for k in range(1, n+1)] for n in range(1, 17)]) # G. C. Greubel, Dec 03 2022

Crossrefs

Cf. A051731.

Sequence in context: A047999 A323378 A054431 * A106470 A106465 A071027

Adjacent sequences: A164378 A164379 A164380 * A164382 A164383 A164384

Keyword

sign,less,tabl

Author

Roger L. Bagula and Mats Granvik, Aug 14 2009

Extensions

Edited by G. C. Greubel, Dec 03 2022

Status

approved