|
| |
|
|
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
|
Patrick De Geest
|
|
|
STATUS
|
approved
|
| |
|
|
