A035132 Nonsquarefree palindromes.
4, 8, 9, 44, 88, 99, 121, 171, 212, 232, 242, 252, 272, 292, 333, 343, 363, 404, 414, 424, 444, 464, 484, 525, 575, 585, 616, 636, 656, 666, 676, 686, 696, 747, 808, 828, 848, 868, 888, 909, 999, 1331, 1881, 2112, 2332, 2552, 2662, 2772, 2992, 3663, 3773
Offset: 1
Examples
4114 = 2 * 11^2 * 17.
Links
- Amiram Eldar, Table of n, a(n) for n = 1..10000
- Eric Weisstein's World of Mathematics, Squarefree.
Crossrefs
Programs
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Mathematica
sfQ[n_]:=Max[Transpose[FactorInteger[n]][[2]]]>1; palQ[n_]:=FromDigits[Reverse[IntegerDigits[n]]]==n; Select[Range[2,3776],sfQ[#] && palQ[#] &] (* Jayanta Basu, May 12 2013 *) Select[Range[4000], PalindromeQ[#] && !SquareFreeQ[#] &] (* Amiram Eldar, Feb 25 2021 *)
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Python
from itertools import product from sympy.ntheory.factor_ import core def palsthru(maxdigits): midrange = [[""], [str(i) for i in range(10)]] for digits in range(1, maxdigits+1): for p in product("0123456789", repeat=digits//2): left = "".join(p) if len(left) and left[0] == '0': continue for middle in midrange[digits%2]: yield int(left+middle+left[::-1]) def okpal(p): return p > 3 and core(p, 2) != p print(list(filter(okpal, palsthru(4)))) # Michael S. Branicky, Apr 08 2021