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 A029992 Numbers k such that k^2 is palindromic in base 7. 13
 0, 1, 2, 4, 8, 10, 11, 20, 32, 40, 50, 57, 64, 80, 160, 200, 344, 400, 500, 550, 557, 730, 1000, 1376, 1432, 1892, 2402, 2451, 2500, 2752, 2801, 3440, 3784, 3902, 5101, 5266, 6880, 8296, 9460, 9608, 9804, 16808, 17200, 19216, 19608, 22693 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 LINKS Marius A. Burtea, Table of n, a(n) for n = 1..237 Patrick De Geest, Palindromic Squares EXAMPLE 8^2 = 64, which is 121 in base 7, and since that's palindromic, 8 is in the sequence. 9^2 = 81, which is 144 in base 7, but since that's not palindromic, 9 is not in the sequence. MATHEMATICA Select[Range[0, 16806], IntegerDigits[#^2, 7] == Reverse[IntegerDigits[#^2, 7]] &] (* Alonso del Arte, Jan 21 2020 *) PROG (Scala) (0 to 16806).filter(n => Integer.toString(n * n, 7) == Integer.toString(n * n, 7).reverse) // Alonso del Arte, Jan 21 2020 (Magma) [k:k in [0..23000]| Seqint(Intseq(k^2, 7)) eq Seqint(Reverse(Intseq(k^2, 7)))]; // Marius A. Burtea, Jan 22 2020 CROSSREFS Cf. A002440 (squares written in base 7), A007093. Numbers k such that k^2 is palindromic in base b: A003166 (b=2), A029984 (b=3), A029986 (b=4), A029988 (b=5), A029990 (b=6), this sequence (b=7), A029805 (b=8), A029994 (b=9), A002778 (b=10), A029996 (b=11), A029737 (b=12), A029998 (b=13), A030072 (b=14), A030073 (b=15), A029733 (b=16), A118651 (b=17). Sequence in context: A070305 A174567 A178330 * A346139 A206928 A133012 Adjacent sequences: A029989 A029990 A029991 * A029993 A029994 A029995 KEYWORD nonn,base AUTHOR STATUS approved

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Last modified February 3 12:24 EST 2023. Contains 360035 sequences. (Running on oeis4.)