A247819 Integers such that A247552(n) is not a repunit.

7, 11, 13, 14, 17, 19, 21, 22, 23, 26, 28, 29, 33, 34, 35, 37, 38, 39, 41, 42, 43, 44, 46, 47, 48, 49, 51, 52, 53, 55, 56, 57, 58, 59, 61, 62, 63, 65, 66, 67, 68, 69, 70, 71, 73, 74, 76, 77, 78, 79, 82, 83, 84, 85, 86, 87, 88, 89, 91, 92, 93, 94, 95, 96, 97

Offset

1,1

Comments

A247552(n) is the least number x such that the ratio of the sum of all the cyclic permutations of x, plus the unpermuted number, and x itself is equal to n.

When x is in the sequence, then all multiples of x are there too. The primitive terms, i.e., the terms that are not a multiple of a previous term, are 7, 11, 13, 17, 19, 23, 29, 37, 41, 43, 47, 48, 53, 59, 61, 62, ... Among those, one finds few composites: 48, 62, 93, 180, 675, 961, ...

Links

Jens Kruse Andersen, Table of n, a(n) for n = 1..1000

Example

A247552(7) is 428571 instead of the more obvious 1111111, so 7 belongs to this sequence.

Prog

(PARI) lista() = my(v = readvec("b247552.txt")); select(x->vecmax(digits(x)) != 1, v, 1);

Crossrefs

Cf. A247552.

Sequence in context: A072823 A110547 A279622 * A051660 A364562 A187040

Adjacent sequences: A247816 A247817 A247818 * A247820 A247821 A247822

Keyword

nonn,base

Author

Michel Marcus, Sep 24 2014

Status

approved