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A237739
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a(0) = 1, a(2n) = nthcomposite(a(n)-1), a(2n+1) = nthprime(a(n)), where nthcomposite = A002808, nthprime = A000040.
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5
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1, 2, 4, 3, 8, 7, 6, 5, 14, 19, 12, 17, 10, 13, 9, 11, 22, 43, 28, 67, 20, 37, 26, 59, 16, 29, 21, 41, 15, 23, 18, 31, 33, 79, 60, 191, 40, 107, 91, 331, 30, 71, 52, 157, 38, 101, 81, 277, 25, 53, 42, 109, 32, 73, 57, 179, 24, 47, 34, 83, 27, 61, 45, 127, 48
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internal format)
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OFFSET
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0,2
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COMMENTS
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LINKS
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FORMULA
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a(0) = 1, a(2n) = nthcomposite(a(n)-1), a(2n+1) = nthprime(a(n)), where nthcomposite = A002808, nthprime = A000040. - Antti Karttunen, Apr 04 2015
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PROG
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(Haskell)
import Data.List (elemIndex); import Data.Maybe (fromJust)
a237739 = fromIntegral . (+ 1) . fromJust . (`elemIndex` a071574_list)
(PARI)
default(primelimit, (2^31)+(2^30));
A002808(n) = { my(k=-1); while( -n + n += -k + k=primepi(n), ); n }; \\ This function from M. F. Hasler
for(n=0, 4095, write("b237739.txt", n, " ", A237739(n)));
(Scheme, with memoizing definec-macro)
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CROSSREFS
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Compare also to the permutation A246378.
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KEYWORD
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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