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A090421 Numbers that can be written in binary representation as concatenation of primes. 9
2, 3, 5, 7, 10, 11, 13, 14, 15, 17, 19, 21, 22, 23, 29, 30, 31, 37, 41, 42, 43, 45, 46, 47, 53, 54, 55, 58, 59, 61, 62, 63, 67, 70, 71, 73, 78, 79, 81, 83, 85, 86, 87, 89, 90, 91, 93, 94, 95, 97, 101, 103, 107, 109, 111, 113, 115, 117, 118, 119, 122, 123 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
A090418(a(n)) > 0; complement of A090419.
Terms in the sequence cannot end in 00, 0010, 001010, etc., and thus a(n) > 3n/2 + O(log n). - Charles R Greathouse IV, Apr 21 2015
LINKS
PROG
(Haskell)
a090421 n = a090421_list !! (n-1)
a090421_list = filter ((> 0) . a090418) [1..]
-- Reinhard Zumkeller, Aug 06 2012
(PARI) is_A090421(n)={isprime(n) || if(bittest(n, 0), for(k=2, #binary(n)-2, bittest(n, k-1) && isprime(n%2^k) && is_A090421(n>>k) && return(1)), bittest(n, 1) && is_A090421(n>>2))} \\ Charles R Greathouse IV and M. F. Hasler, Apr 21 2015
CROSSREFS
Cf. A000040, A090420, and A090423 are subsequences.
Sequence in context: A298746 A122428 A087246 * A109608 A325388 A325405
KEYWORD
nonn,base
AUTHOR
Reinhard Zumkeller, Nov 30 2003
EXTENSIONS
Based on corrections in A090418, data recomputed by Reinhard Zumkeller, Aug 06 2012
STATUS
approved

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Last modified February 29 16:02 EST 2024. Contains 370425 sequences. (Running on oeis4.)