A006447 Consider a 2-D cellular automaton generated by the Schrandt-Ulam rule of A170896, but confined to a semi-infinite strip of width n, starting with one ON cell at the top left corner; a(n) is the period of the resulting structure.

1, 2, 3, 5, 5, 8, 13, 13, 13, 26, 13, 91, 13, 106, 106, 75, 93, 62, 80, 132, 337, 416, 62, 62, 62, 271, 34, 155, 525, 548, 1084, 115, 62, 558, 62, 1500, 2922, 124, 2958, 3374, 2323, 4183, 8073, 7925, 744, 2298, 434, 6700, 310, 23796, 12732, 26405

Offset: 1

Author

N. J. A. Sloane

Keywords

• nonn

Comments

Schrandt and Ulam remark that there seems to be no simple relation between n and a(n).

The original report included two further terms, but they were omitted from the published version, so are presumably unreliable.

References

• N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Links

• J. T. Butler, Letter to N. J. A. Sloane, Jun. 1975.
• R. G. Schrandt and S. M. Ulam, On recursively defined geometric objects and patterns of growth, Los Alamos Scientific Laboratory, Report LA-3762, Aug 16 1967; published in A. W. Burks, editor, Essays on Cellular Automata. Univ. Ill. Press, 1970, pp. 238ff. [Link supplied by Laurinda J. Alcorn, Jan 09 2010]
• Index entries for sequences related to cellular automata

Extensions

Entry revised by N. J. A. Sloane, Jan 09 2010

More terms from Sean A. Irvine, Apr 13 2017