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A225648 Positions of ones in A225650, numbers n such that n and A000793(n) are coprime. 6
0, 1, 5, 7, 8, 9, 11, 13, 17, 19, 23, 27, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97, 101, 103, 107, 109, 113, 127, 131, 137, 139, 149, 151, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199, 211, 223, 227, 229, 233, 239, 241, 251, 257, 263, 269, 271, 277, 281, 283, 293, 307, 311, 313 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

Contains all primes from 5 onward. Are 8, 9 and 27 only composite numbers present?

LINKS

Alois P. Heinz, Table of n, a(n) for n = 1..5000

MATHEMATICA

b[n_, i_] := b[n, i] = Module[{p}, p = If[i < 1, 1, Prime[i]]; If[n == 0 || i < 1, 1, Max[b[n, i - 1], Table[p^j*b[n - p^j, i - 1], {j, 1, Log[p, n] // Floor}]]]]; g[n_] := b[n, If[n < 8, 3, PrimePi[Ceiling[1.328*Sqrt[n* Log[n] // Floor]]]]]; Join[{0}, Position[Table[GCD[n, g[n]], {n, 1, 500} ], 1] // Flatten] (* Jean-Fran├žois Alcover, Mar 03 2016, after Alois P. Heinz *)

PROG

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

(define A225648 (MATCHING-POS 1 1 (lambda (i) (= 1 (gcd (A000793 i) i)))))

CROSSREFS

Complement: A225649. Cf. also A225650.

Sequence in context: A118742 A122904 A104693 * A031221 A137469 A043353

Adjacent sequences:  A225645 A225646 A225647 * A225649 A225650 A225651

KEYWORD

nonn

AUTHOR

Antti Karttunen, May 12 2013

STATUS

approved

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Last modified July 21 02:02 EDT 2019. Contains 325189 sequences. (Running on oeis4.)