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A091308
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Primes in A038395 (concatenate first n odd numbers in reverse order).
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1
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31, 737169676563615957555351494745434139373533312927252321191715131197531, 12312111911711511311110910710510310199979593918987858381797775737169676563615957555351494745434139373533312927252321191715131197531
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OFFSET
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1,1
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COMMENTS
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Among the first 72 terms only three terms are prime SmBackConOdd(2), SmBackConOdd(37) and SmBackConOdd(62), found by Micha Fleuren.
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LINKS
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MAPLE
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x:= 1: d:= 1: count:= 0: R:= NULL:
for i from 2 while count < 5 do
x:= (2*i-1)*10^d + x;
d:= d + ilog10(2*i-1)+1;
if isprime(x) then count:= count+1; R:= R, x; fi;
od:
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MATHEMATICA
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Select[Table[FromDigits[Flatten[IntegerDigits/@Range[n, 1, -2]]], {n, 1, 341, 2}], PrimeQ] (* Harvey P. Dale, Jul 12 2022 *)
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CROSSREFS
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KEYWORD
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nonn,bref,base,changed
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AUTHOR
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M. Grete (martha.grete(AT)web.de), Feb 21 2004
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EXTENSIONS
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Definition corrected by XU Pingya, Mar 16 2017
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STATUS
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approved
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