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A121559 Final result (0 or 1) under iterations of {r mod (max prime p <= r)} starting at r = n. 7
1, 0, 0, 1, 0, 1, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 1, 0, 0, 1, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0, 1, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0, 1, 0, 1, 0, 0, 1, 0, 0, 0, 1, 0, 1, 0 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Previous name: Find r1 = n modulo p1, where p1 is the largest prime not greater than n. Then find r2 = r1 modulo p2, where p2 is the largest prime not greater than r1. Repeat until the last r is either 1 or 0; a(n) is the last r value.

The sequence has the form of blocks of 0's between 1's. See sequence A121560 for the lengths of the blocks of zeros.

LINKS

Kerry Mitchell, Table of n, a(n) for n = 1..7919

FORMULA

a(p) = 0 when p is prime. - Michel Marcus, Aug 22 2014

EXAMPLE

a(9) = 0 because 7 is the largest prime not larger than 9, 9 mod 7 = 2, 2 is the largest prime not greater than 2 and 2 mod 2 = 0.

PROG

(PARI) a(n) = if (n==1, return (1)); na = n; while((nb = (na % precprime(na))) > 1, na = nb); return(nb); \\ Michel Marcus, Aug 22 2014

CROSSREFS

Cf. A007917 and A064722 (both for the iterations).

Cf. A121560, A121561, A121562.

Sequence in context: A244612 A105367 A065043 * A004641 A100810 A174889

Adjacent sequences:  A121556 A121557 A121558 * A121560 A121561 A121562

KEYWORD

easy,nonn

AUTHOR

Kerry Mitchell, Aug 07 2006

EXTENSIONS

New name from Michel Marcus, Aug 22 2014

STATUS

approved

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Last modified November 1 07:15 EDT 2014. Contains 248888 sequences.