A172199 - OEIS

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A172199

Number of numbers with 2n+1 digits that are lunar squares.

10, 90, 900, 9000, 74667, 608673

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

COMMENTS

Every lunar square (see A087019) has an odd number of digits. Lunar squares with <= 7 digits are all distinct, but for longer numbers there are many examples of pairs of numbers whose lunar squares coincide.

LINKS

Table of n, a(n) for n=1..6.

D. Applegate, M. LeBrun and N. J. A. Sloane, Dismal Arithmetic [Note: we have now changed the name from "dismal arithmetic" to "lunar arithmetic" - the old name was too depressing]

Index entries for sequences related to dismal (or lunar) arithmetic

CROSSREFS

Cf. A087019, A180513, A181319.

Sequence in context: A199527 A137684 A097394 * A063945 A218127 A322647

Adjacent sequences: A172196 A172197 A172198 * A172200 A172201 A172202

KEYWORD

nonn,base,more

AUTHOR

David Applegate, Marc LeBrun and N. J. A. Sloane, Jan 20 2011

STATUS

approved