

A159555


Numbers n where n^2 divides A159553(n), where A159553(n) = sum{k=0 to n} binomial(n,k) * GCD(n,k).


0



1, 6, 22, 72, 114, 148, 164, 260, 261, 780, 1078, 1184, 1266, 2952, 4674
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OFFSET

1,2


COMMENTS

For the purpose of this sequence, GCD(n,0) = n.


LINKS

Table of n, a(n) for n=1..15.


MAPLE

A159068 := proc(n) option remember; add(binomial(n, k)*gcd(k, n), k=1..n) ; end: A159553 := proc(n) option remember ; A159068(n)+n; end: isA159555 := proc(n) if A159553(n) mod ( n^2) = 0 then true; else false; fi; end: for n from 1 do if isA159555(n) then printf("%d, \n", n) ; fi; od: [From R. J. Mathar, Apr 29 2009]


CROSSREFS

Cf. A159553, A159554, A159458.
Sequence in context: A171495 A178706 A276779 * A032195 A217530 A111566
Adjacent sequences: A159552 A159553 A159554 * A159556 A159557 A159558


KEYWORD

nonn


AUTHOR

Leroy Quet, Apr 15 2009


EXTENSIONS

Extended by R. J. Mathar, Apr 29 2009
a(14)a(15) from Ray Chandler, Jun 18 2009


STATUS

approved



