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A175128
a(n) = the number of natural numbers m with n steps of iterations of {r - (smallest prime divisor of r)} needed to reach 0 starting at r = m .
0
1, 1, 2, 1, 1, 2, 1, 1, 2, 2, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 2, 1, 2, 1, 1, 3
OFFSET
2,3
COMMENTS
EXAMPLE
Example (a(7)=2): There are two natural numbers 14 and 15 with 7 steps in this iteration. 14-2=12, 12-2=10, 10-2=8, 8-2=6, 6-2=4, 4-2=2, 2-2=0; 15-3=12, 12-2=10, 10-2=8, 8-2=6, 6-2=4, 4-2=2, 2-2=0.
CROSSREFS
Sequence in context: A182907 A334745 A323231 * A359307 A205154 A337772
KEYWORD
nonn
AUTHOR
Jaroslav Krizek, Feb 15 2010
STATUS
approved