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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 Reinhard Zumkeller, Table of n, a(n) for n = 1..10000 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. A004676, A007088, A090422. Cf. A000040, A090420, and A090423 are subsequences. Sequence in context: A298746 A122428 A087246 * A109608 A325388 A325405 Adjacent sequences: A090418 A090419 A090420 * A090422 A090423 A090424 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.)