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A170892 Toothpick sequence similar to A160406, but always staying outside the wedge, starting at stage 1 with a vertical toothpick whose endpoint touches the vertex of the wedge. 5
0, 1, 2, 4, 8, 12, 16, 24, 34, 44, 48, 56, 66, 78, 90, 112, 138, 156, 160, 168, 178, 190, 202, 224, 250, 270, 282, 304, 332, 364, 406, 472, 538, 572, 576, 584, 594, 606, 618, 640, 666, 686, 698, 720, 748, 780, 822, 888, 954, 990, 1002, 1024, 1052, 1084, 1126, 1192, 1260, 1308, 1350, 1418, 1502, 1604, 1750, 1944 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

See A170893 for the first differences.

LINKS

Table of n, a(n) for n=0..63.

David Applegate, Omar E. Pol and N. J. A. Sloane, The Toothpick Sequence and Other Sequences from Cellular Automata

N. J. A. Sloane, Catalog of Toothpick and Cellular Automata Sequences in the OEIS

PROG

(PARI) A170892(n, print_all=0)={my( ee=[[2*I, I]], p=Set( concat( vector( 2*n-(n>0), k, k-n-abs(k-n)*I ), I )), cnt=2); print_all & print1("1, 2"); n<3 & return(n); for(i=3, n, p=setunion(p, Set(Mat(ee~)[, 1])); my(c, d, ne=[]); for( k=1, #ee, setsearch(p, c=ee[k][1]+d=ee[k][2]*I) || ne=setunion(ne, Set([[c, d]])); setsearch(p, c-2*d) || ne=setunion(ne, Set([[c-2*d, -d]]))); forstep( k=#ee=eval(ne), 2, -1, ee[k][1]==ee[k-1][1] & k-- & ee=vecextract(ee, Str("^"k"..", k+1))); cnt+=#ee; print_all & print1(", "cnt)); cnt} \\ - M. F. Hasler, Jan 30 2013

CROSSREFS

Cf. A139250, A160406, A170886, A170888, A170890, A170893.

Sequence in context: A069519 A087980 A181818 * A246468 A052184 A152768

Adjacent sequences:  A170889 A170890 A170891 * A170893 A170894 A170895

KEYWORD

nonn

AUTHOR

Omar E. Pol, Jan 09 2010

EXTENSIONS

Terms beyond a(10) from M. F. Hasler, Jan 30 2013

STATUS

approved

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Last modified February 24 18:24 EST 2018. Contains 299628 sequences. (Running on oeis4.)