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A033294 Squares which when written backwards remain square (final 0's excluded). 4
1, 4, 9, 121, 144, 169, 441, 484, 676, 961, 1089, 9801, 10201, 10404, 10609, 12321, 12544, 12769, 14641, 14884, 40401, 40804, 44521, 44944, 48841, 69696, 90601, 94249, 96721, 698896, 1002001, 1004004, 1006009, 1022121, 1024144, 1026169 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 1..1000

Index entry for sequences related to reversing digits of squares

EXAMPLE

144 = 12 * 12 is a term because 441 = 21 * 21

MATHEMATICA

Select[Range[1100]^2, Mod[#, 10]!=0&&IntegerQ[Sqrt[FromDigits[Reverse[ IntegerDigits[ #]]]]]&] (* Harvey P. Dale, Oct 28 2013 *)

PROG

(Haskell)

a033294 n = a033294_list !! (n-1)

a033294_list = filter chi a000290_list where

  chi m = m `mod` 10 > 0 && head ds `elem` [1, 4, 5, 6, 9] &&

          a010052 (foldl (\v d -> 10 * v + d) 0 ds) == 1 where

    ds = unfoldr

         (\x -> if x == 0 then Nothing else Just $ swap $ divMod x 10) m

-- Reinhard Zumkeller, Jan 19 2012

CROSSREFS

Cf. A007488, A007500.

Sequence in context: A042649 A042381 A230743 * A156317 A115676 A115667

Adjacent sequences:  A033291 A033292 A033293 * A033295 A033296 A033297

KEYWORD

base,nonn

AUTHOR

Jeff Burch

EXTENSIONS

More terms from Erich Friedman.

Initial 0 removed and offset changed by Reinhard Zumkeller, Jan 19 2012

STATUS

approved

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Last modified December 13 14:58 EST 2017. Contains 295958 sequences.