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A328837
Numbers k for which A328403(k) = A276086(A276086(A276086(k))) is squarefree.
1
0, 1, 2, 4, 9, 2312
OFFSET
1,3
COMMENTS
Numbers k such that A276086(k) is in A328836, or equally, that A276087(k) is in A276156, i.e., numbers k for which A328828(A276087(k)) is zero, that is, numbers k such that in the primorial base expansion of A276087(k) there are no digits larger than 1.
All the terms of A328313 are also included in this sequence. Questions: Is that sequence finite? Even if it is, is this one also? Are there any terms here between 2312 and 3217644767340672907899084554132? Are there only finitely many numbers k for which A328828(A328403(k)) is zero? (See comments in A328398.)
PROG
(PARI)
A276086(n) = { my(m=1, p=2); while(n, m *= (p^(n%p)); n = n\p; p = nextprime(1+p)); (m); };
A328828(n) = { my(i=1, p=2); while(n, if((n%p)>1, return(i)); i++; n = n\p; p = nextprime(1+p)); (0); };
isA328837(n) = !A328828(A276086(A276086(n)));
CROSSREFS
Positions of ones in A328394. See also comments in A328398.
Sequence in context: A292114 A128942 A364637 * A302349 A135445 A098556
KEYWORD
nonn,hard,more
AUTHOR
Antti Karttunen, Oct 30 2019
STATUS
approved