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 A077439 Numbers n such that n and n^2 have square decimal digits. 3
 0, 1, 10, 100, 1000, 1049, 10000, 10490, 100000, 100499, 104900, 1000000, 1004990, 1049000, 10000000, 10004999, 10049900, 10490000, 100000000, 100049990, 100499000, 104900000, 1000000000, 1000049999, 1000499900, 1004990000, 1044049999, 1049000000, 10000000000, 10000499990, 10004999000, 10049900000, 10440499990 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS Numbers n such that n and the square of n use only the digits 0, 1, 4 and 9. Notice the trick used in the first Mathematica program to convert decimal numbers to base 4 numbers and then map threes into nines and then twos into fours. This saves a lot of computing. - Robert G. Wilson v, Nov 08 2002 LINKS Jonathan Wellons, Table of n, a(n) for n=1..68 J. Wellons, Tables of Shared Digits EXAMPLE 1049^2 = 1100401, therefore 1049 is a term; whereas A046030(6)=14 is not a term, as 14^2=196 and 6 is not a square digit. 104900499999000^2 = 11004114900040199000001000000 MATHEMATICA a = {}; Do[d = FromDigits[ ReplaceAll[ IntegerDigits[n, 4], {3 -> 9, 2 -> 4}]]; If[ Union[ Join[ IntegerDigits[d^2], {0, 1, 4, 9}]] == {0, 1, 4, 9}, a = Append[a, d]], {n, 0, 3*10^5}]; a With[{c={0, 1, 4, 9}}, Select[FromDigits/@Tuples[c, 11], SubsetQ[c, IntegerDigits[ #^2]]&]] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Jan 15 2017 *) CROSSREFS A077440(n) = a(n)^2. Cf. A046030, A019544, A000290. Sequence in context: A115814 A171758 A115798 * A136839 A136863 A031201 Adjacent sequences:  A077436 A077437 A077438 * A077440 A077441 A077442 KEYWORD base,nonn AUTHOR Reinhard Zumkeller, Nov 06 2002 EXTENSIONS Edited by Robert G. Wilson v, Nov 08 2002 More terms from Jonathan Wellons (wellons(AT)gmail.com), Jan 22 2008 Edited by N. J. A. Sloane, May 15 2008 at the suggestion of R. J. Mathar. STATUS approved

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Last modified June 5 18:48 EDT 2020. Contains 334854 sequences. (Running on oeis4.)