A082693 Pyramidal sequence built with powers of 2.

1, 2, 1, 2, 4, 2, 1, 2, 4, 8, 4, 2, 1, 2, 4, 8, 16, 8, 4, 2, 1, 2, 4, 8, 16, 32, 16, 8, 4, 2, 1, 2, 4, 8, 16, 32, 64, 32, 16, 8, 4, 2, 1, 2, 4, 8, 16, 32, 64, 128, 64, 32, 16, 8, 4, 2, 1, 2, 4, 8, 16, 32, 64, 128, 256, 128, 64, 32, 16, 8, 4, 2, 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 256, 128

Offset

1,2

Links

Table of n, a(n) for n=1..84.

Example

Triangle begins:
                                 1
                               2 1 2
                             4 2 1 2 4
                           8 4 2 1 2 4 8
                        16 8 4 2 1 2 4 8 16
                     32 16 8 4 2 1 2 4 8 16 32
                  64 32 16 8 4 2 1 2 4 8 16 32 64
              128 64 32 16 8 4 2 1 2 4 8 16 32 64 128
          256 128 64 32 16 8 4 2 1 2 4 8 16 32 64 128 256
      512 256 128 64 32 16 8 4 2 1 2 4 8 16 32 64 128 256 512
1024 512 256 128 64 32 16 8 4 2 1 2 4 8 16 32 64 128 256 512 1024
... - Philippe Deléham, Mar 20 2013

Mathematica

pow2Pyram[row_] := Module[{st = 2^Range[0, row]}, Join[st, Reverse[Most[Rest[st]]]]]; Flatten[Array[pow2Pyram, 10]] (* Harvey P. Dale, May 09 2012 *)
Flatten[Table[Table[2^Abs[col], {col, -row, row}], {row, 0, 7}]] (* Alonso del Arte, Apr 15 2017 *)

Prog

(PARI) for(i=0, 9, forstep(j=i, 0, -1, print1(1<<j", ")); for(j=1, i, print1(1<<j", "))) \\ Charles R Greathouse IV, Mar 20 2013

Crossrefs

Cf. A004738, A082693 (partial sums), A036563 (row sums).

Sequence in context: A186187 A013943 A164281 * A225081 A307368 A097082

Adjacent sequences: A082690 A082691 A082692 * A082694 A082695 A082696

Keyword

nonn,tabf,easy

Author

Benoit Cloitre, Apr 12 2003

Status

approved