A071251 Squarefree palindromes.

1, 2, 3, 5, 6, 7, 11, 22, 33, 55, 66, 77, 101, 111, 131, 141, 151, 161, 181, 191, 202, 222, 262, 282, 303, 313, 323, 353, 373, 383, 393, 434, 454, 474, 494, 505, 515, 535, 545, 555, 565, 595, 606, 626, 646, 707, 717, 727, 737, 757, 767, 777, 787, 797, 818, 838

Offset

1,2

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000

Maple

ffpal := proc(n) local i, j, k, s, aa, nn, bb, flag; s := n; aa := convert(s, string); nn := length(aa); bb := ``; for i from nn by -1 to 1 do bb := cat(bb, substring(aa, i..i)); od; flag := 0; for j from 1 to nn do if substring(aa, j..j)<>substring(bb, j..j) then flag := 1 fi; od; RETURN(flag); end: ts_ndk_pal := proc(i) if ffpal((i)) = 0 then if (numtheory[issqrfree](i) = 'true' ) then RETURN((i)) fi fi end: andkpal := [seq(ts_ndk_pal(i), i=1..10000)]: andkpal;

Mathematica

Select[ Range[ 1000], # == FromDigits[ Reverse[ IntegerDigits[ # ]]] && Max[ Transpose[ FactorInteger[ # ]] [[2]]] < 2 &]
Select[Range[1000], PalindromeQ[#]&&SquareFreeQ[#]&] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Dec 17 2018 *)

Crossrefs

Intersection of A002113 and A005117.

Cf. A002385, A069217, A032350, A035132.

Sequence in context: A331394 A273524 A098959 * A077571 A101730 A276692

Adjacent sequences: A071248 A071249 A071250 * A071252 A071253 A071254

Keyword

base,nonn

Author

Amarnath Murthy, May 21 2002

Extensions

Edited by Robert G. Wilson v, Jun 03 2002

Status

approved