A235050 - OEIS

A235050

Squarefree numbers such that none of their prime factors share common 1-bits in the same bit-position of their binary representations.

1, 2, 3, 5, 7, 10, 11, 13, 17, 19, 23, 26, 29, 31, 34, 37, 41, 43, 47, 53, 58, 59, 61, 67, 71, 73, 74, 79, 82, 83, 89, 97, 101, 103, 106, 107, 109, 113, 122, 127, 131, 137, 139, 146, 149, 151, 157, 163, 167, 173, 178, 179, 181, 191, 193, 194, 197, 199, 202, 211, 218, 223, 226, 227, 229, 233, 239, 241, 251, 257

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OFFSET

1,2

COMMENTS

a(1)=1 is included on the grounds that it has no prime factors at all, thus no conflicting 1-bits.

After a(1)=1 all n such that A001414(n) = A072593(n), or equally, A001414(n) = A072594(n).

Union of noncomposites (A008578) and semiprimes of the form 2*A002144 (cf. also A235490).

LINKS

Antti Karttunen, Table of n, a(n) for n = 1..10000

PROG

(Scheme, with Antti Karttunen's IntSeq-library)

(define A235050 (MATCHING-POS 1 1 (lambda (n) (or (= 1 n) (= (A001414 n) (A072593 n))))))

CROSSREFS

Subsequences: A000040, A235490.

Subsequence of A005117.

Cf. also A001414, A072593, A072594, A235040.

Sequence in context: A187711 A064627 A324813 * A117286 A169802 A194948

Adjacent sequences: A235047 A235048 A235049 * A235051 A235052 A235053

KEYWORD

nonn,easy

AUTHOR

Antti Karttunen, Jan 22 2014

STATUS

approved