

A107949


Smallest k_n such that there exist positive integers 0 < k_1 < ... < k_n such that there exists only one ntuple of nonnegative integers (b_1, ..., b_n)  namely (1, ..., 1)  such that the sum of the b_i's equals n and the sum of the b_i*k_i's equals the sum of the k_i's.


0




OFFSET

1,2


COMMENTS

These are instances that show that the sequence is at most what is given: 1, 1+2, 1+2+4, 1+2+5+7, 1+2+6+12+14, 1+3+11+22+23+27, 1+2+6+22+44+46+54.


LINKS

Table of n, a(n) for n=1..7.


EXAMPLE

a(3)=4 because 1+2+3 = 2+2+2 but you can't write 1+2+4 as the sum of three numbers in {1,2,4} in another way.
a(4)=7 because, for instance, 2+4+5+6 = 2+5+5+5 but I'll let you check that you can't write 1+2+5+7 as the sum of four numbers in {1,2,5,7}, unless of course you take each one once.


CROSSREFS

Sequence in context: A018085 A167751 A190822 * A155099 A136322 A160113
Adjacent sequences: A107946 A107947 A107948 * A107950 A107951 A107952


KEYWORD

hard,nonn


AUTHOR

Vincent Nesme (vnesme(AT)enslyon.fr), May 28 2005


STATUS

approved



