A173537 a(n) = A173522(n)/2.

2, 4, 7, 10, 13, 17, 23, 28, 31, 35, 41, 47, 53, 61, 73, 82, 85, 89, 95, 101, 107, 115, 127, 137, 143, 151, 163, 175, 187, 203, 227, 244, 247, 251, 257, 263, 269, 277, 289, 299, 305, 313, 325, 337, 349, 365, 389, 407, 413, 421, 433, 445, 457, 473, 497, 517, 529, 545, 569, 593, 617, 649, 697, 730, 733, 737, 743, 749, 755, 763, 775, 785, 791, 799, 811, 823, 835

Offset: 2

Author

Omar E. Pol, May 29 2010

Keywords

• nonn

Links

• David Applegate, Omar E. Pol and N. J. A. Sloane, The Toothpick Sequence and Other Sequences from Cellular Automata, Congressus Numerantium, Vol. 206 (2010), 157-191. [There is a typo in Theorem 6: (13) should read u(n) = 4.3^(wt(n-1)-1) for n >= 2.]
• N. J. A. Sloane, Catalog of Toothpick and Cellular Automata Sequences in the OEIS

Crossrefs

Cf. A105321, A139250, A173522.

Programs

Mathematica

f[n_] := f[n] = Sum[Binomial[1, n - k] Mod[ Binomial[k, j], 2], {k, 0, n}, {j, 0, k}]; g[n_] := Sum[f@k, {k, 0, n}]; Array[g, 77]/2

Extensions

I changed the title (its index), the offset, extended the sequence and added the Mathematica coding Robert G. Wilson v, Jun 28 2010