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A249156
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Palindromic in bases 5 and 7.
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20
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0, 1, 2, 3, 4, 6, 24, 57, 78, 114, 342, 624, 856, 1432, 10308, 12654, 27616, 100056, 537856, 593836, 769621, 1434168, 1473368, 1636104, 1823544, 1862744, 17968646, 18108296, 22412057, 34713713, 34853363, 39280254, 159690408, 663706192
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OFFSET
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1,3
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COMMENTS
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LINKS
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EXAMPLE
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114 is a term since 114 = 424 base 5 and 114 = 222 base 7.
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MATHEMATICA
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palQ[n_Integer, base_Integer]:=Block[{idn=IntegerDigits[n, base]}, idn==Reverse[idn]]; Select[Range[10^6]-1, palQ[#, 5]&&palQ[#, 7]&]
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PROG
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(Python)
from gmpy2 import digits
def palQ(n, b): # check if n is a palindrome in base b
s = digits(n, b)
return s == s[::-1]
def palQgen(l, b): # unordered generator of palindromes in base b of length <= 2*l
if l > 0:
yield 0
for x in range(1, b**l):
s = digits(x, b)
yield int(s+s[-2::-1], b)
yield int(s+s[::-1], b)
A249156_list = sorted([n for n in palQgen(8, 5) if palQ(n, 7)]) # Chai Wah Wu, Nov 25 2014
(PARI) isok(n) = my(df = digits(n, 5), ds = digits(n, 7)); (Vecrev(df)==df) && (Vecrev(ds)==ds); \\ Michel Marcus, Oct 31 2017
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CROSSREFS
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KEYWORD
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nonn,base
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AUTHOR
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STATUS
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approved
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