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A000787 Strobogrammatic numbers: the same upside down.
(Formerly M4480 N1897)
21
0, 1, 8, 11, 69, 88, 96, 101, 111, 181, 609, 619, 689, 808, 818, 888, 906, 916, 986, 1001, 1111, 1691, 1881, 1961, 6009, 6119, 6699, 6889, 6969, 8008, 8118, 8698, 8888, 8968, 9006, 9116, 9696, 9886, 9966, 10001, 10101, 10801, 11011, 11111, 11811, 16091 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

Strobogrammatic numbers are a kind of ambigrams that retain the same meaning when viewed upside down.- Daniel Mondot, Sep 27 2016

"Upside down" here means rotated by 180° (i.e., central symmetry), NOT "vertically flipped" (symmetry w.r.t. horizontal line). - M. F. Hasler, May 04 2012

REFERENCES

N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).

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

LINKS

T. D. Noe, Table of n, a(n) for n=1..1000

J. M. Howell, Strobogrammatic years, Math. Mag., 34 (1961), p. 182 and 184.

MATHEMATICA

fQ[n_] := Block[{s = {0, 1, 6, 8, 9}, id = IntegerDigits[n]}, If[ Union[ Join[s, id]] == s && (id /. {6 -> 9, 9 -> 6}) == Reverse[id], True, False]]; Select[ Range[0, 16190], fQ[ # ] &] (* Robert G. Wilson v *)

CROSSREFS

Cf. A007597 (Primes in this sequence), A057770, A111065, A169731 (another version).

Subsequence of A045574. - M. F. Hasler, May 04 2012

Sequence in context: A107788 A038289 A079607 * A188000 A167621 A006072

Adjacent sequences:  A000784 A000785 A000786 * A000788 A000789 A000790

KEYWORD

base,nonn,easy

AUTHOR

N. J. A. Sloane.

EXTENSIONS

More terms from Robert G. Wilson v, Oct 11 2005

STATUS

approved

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Last modified December 7 11:34 EST 2016. Contains 278874 sequences.