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A071590
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Numbers k such that reversal(k) < k.
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9
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10, 20, 21, 30, 31, 32, 40, 41, 42, 43, 50, 51, 52, 53, 54, 60, 61, 62, 63, 64, 65, 70, 71, 72, 73, 74, 75, 76, 80, 81, 82, 83, 84, 85, 86, 87, 90, 91, 92, 93, 94, 95, 96, 97, 98, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 201, 210, 211, 220, 221, 230, 231
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OFFSET
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1,1
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LINKS
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MATHEMATICA
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Select[Range[300], # > FromDigits[Reverse[IntegerDigits[#]]] &] (* T. D. Noe, Mar 14 2012 *)
Select[Range[300], IntegerReverse[#]<#&] (* Harvey P. Dale, Jan 16 2022 *)
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PROG
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(PARI) for(i=2, 300, n=(i); s=ceil(log(n)/log(10)); if((sum(i=0, s, 10^(s-i-1)*(floor(n/10^i*1.)-10*floor(n/10^(i+1)*1.))))<i, print1((i), ", ")))
(PARI) is(n) = {fromdigits(Vecrev(digits(n)))<n} \\ David A. Corneth, Apr 07 2021
(Python)
def ok(n): return int(str(n)[::-1]) < n
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CROSSREFS
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Cf. A161602 (binary reversal(k) < k).
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KEYWORD
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nonn,easy,base
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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