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A069354
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Lowest base with simple divisibility test for n primes; smallest B such that omega(B) + omega(B-1) = n.
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2
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2, 3, 6, 15, 66, 210, 715, 7315, 38571, 254541, 728365, 11243155, 58524466, 812646121, 5163068911, 58720148851, 555409903686, 4339149420606, 69322940121436, 490005293940085, 5819629108725510, 76622240600506315
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listen;
history;
text;
internal format)
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OFFSET
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1,1
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COMMENTS
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Indices of record values of primepi(n) - A181834(n) (the number of primes <= n which are not strongly prime to n). - Peter Luschny, Mar 17 2013
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LINKS
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FORMULA
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EXAMPLE
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a(4) = 15 because in base 15 you can test for divisibility by 4 different primes (3 and 5 directly, 2 and 7 by "casting out 14's")
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MAPLE
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A069354_list := proc(n) local i, L, Max; Max := 1; L := NULL;
for i from 2 to n do
if nops(numtheory[factorset](i*(i-1))) = Max
then Max := Max + 1; L := L, i fi;
od;
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CROSSREFS
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KEYWORD
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nonn,more
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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