

A248145


Consider the partition of the positive odd integers into minimal blocks such that concatenation of numbers in each block is a number of the form 3^k*prime, k>=0. Sequence lists numbers of odd integers in the blocks.


4



2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 3, 1, 1, 2, 1, 1, 1, 1, 1, 2, 1, 2, 1, 1, 1, 3, 1, 1, 2, 1, 1, 1, 7, 1, 1, 1, 2, 1, 1, 1, 2
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OFFSET

1,1


COMMENTS

3^m, m>=1, is of the considered form 3^k*prime, k=m1>=0, prime=3.
The first blocks of the partition are 1,3,5,7,9,11,13,15,17,19,21,23,25,27,29,31,33,35,37,...


LINKS

Table of n, a(n) for n=1..42.


EXAMPLE

The 12th block of partition is 25,27,29, since we have 25=5^2, 2527=7*19^2, 252729=3^2*28081, and only the last number is of the required form. So a(12)=3.


CROSSREFS

Cf. A103899, A248146.
Sequence in context: A069347 A161606 A300362 * A171398 A113607 A082586
Adjacent sequences: A248142 A248143 A248144 * A248146 A248147 A248148


KEYWORD

nonn,base,more


AUTHOR

Vladimir Shevelev, Oct 02 2014


STATUS

approved



