A136724 Numbers divisible by 4 that are not powers of 2.

12, 20, 24, 28, 36, 40, 44, 48, 52, 56, 60, 68, 72, 76, 80, 84, 88, 92, 96, 100, 104, 108, 112, 116, 120, 124, 132, 136, 140, 144, 148, 152, 156, 160, 164, 168, 172, 176, 180, 184, 188, 192, 196, 200, 204, 208, 212, 216, 220, 224, 228, 232, 236, 240, 244, 248

Offset

1,1

Comments

Primitive dimensions of Hadamard matrices which cannot be obtained as tensor powers of the primitive matrix 2 X 2 {{1,1},{1,-1}}.

5+7=12=2+4+6, 9+11=20=2+4+6+8,.. Numbers that can be expressed as sum of two or more positive consecutive odd numbers AND as sums of two or more positive consecutive even numbers. - Vladimir Joseph Stephan Orlovsky, May 11 2010

Numbers in A008586 but not in A000079. - Michel Marcus, Nov 07 2013

Nicomachus called these numbers "odd-times even". - Eric M. Schmidt, Mar 30 2019

Links

Table of n, a(n) for n=1..56.

Nicomachus, Introduction to Arithmetic, Book I, Chapter X.

Mathematica

a = {}; Do[k = 4n; If[Round[Log[k]/Log[2]] == Log[k]/Log[2], [null], AppendTo[a, k]], {n, 1, 100}]; a

Crossrefs

Cf. A007299.

Cf. A000079, A008586.

Sequence in context: A206552 A332832 A065201 * A361868 A316597 A329142

Adjacent sequences: A136721 A136722 A136723 * A136725 A136726 A136727

Keyword

nonn

Author

Artur Jasinski, Jan 19 2008

Status

approved