A090421 Numbers that can be written in binary representation as concatenation of primes.

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

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