A228147 Triangle T(n,k), read by rows: T(n,k) is the denominator of (1+2^(n-k+1))/(1-2^(k+1)).

1, 1, 1, 1, 3, 7, 1, 1, 7, 5, 1, 3, 7, 3, 31, 1, 1, 7, 5, 31, 21, 1, 3, 7, 15, 31, 63, 127, 1, 1, 7, 5, 31, 7, 127, 85, 1, 3, 7, 3, 31, 63, 127, 51, 511, 1, 1, 7, 5, 31, 21, 127, 85, 511, 341, 1, 3, 7, 15, 31, 63, 127, 15, 511, 1023, 2047, 1, 1, 7, 5, 31

Offset

0,5

Comments

The numerators are given in A228146.

The first diagonal is A213243, the second diagonal is A213244, the third diagonal is A213246, the fourth diagonal is A213247.

Links

Vincenzo Librandi, Rows n = 0..100, flattened

Example

Triangle begins:
1;
1,1;
1,3,7;
1,1,7,5;
1,3,7,3,31;
1,1,7,5,31,21;
1,3,7,15,31,63,127;
1,1,7,5,31,7,127,85;
1,3,7,3,31,63,127,51,511;
1,1,7,5,31,21,127,85,511,341;
1,3,7,15,31,63,127,15,511,1023,2047;
1,1,7,5,31,21,127,85,511,341,2047,1365; etc.

Mathematica

a[n_, k_] := Denominator[(1 + 2^(n - k + 1))/(1 - 2^(k + 1))]; Table[a[n, k], {n, 0, 11}, {k, 0, n}] // Flatten

Prog

(Magma) [Denominator((1+2^(n-k+1))/(1-2^(k+1))): k in [0..n], n in [0..11]];

Crossrefs

Cf. A213243, A213244, A213246, A213247.

Sequence in context: A085785 A200235 A127929 * A200922 A210453 A003118

Adjacent sequences: A228144 A228145 A228146 * A228148 A228149 A228150

Keyword

nonn,tabl

Author

Vincenzo Librandi, Aug 15 2013

Status

approved