A254035 - OEIS

%I #31 Apr 14 2015 10:28:34

%S 4800,28800,57600,67200,86400,96000,115200,142800,144000,148800,

%T 153600,182400,201600,211200,230400,259200,288000,297600,326400,

%U 345600,355200,384000,403200,432000,470400,489600,499200,518400,528000,547200,576000,614400,633600,638400,662400,672000,691200,720000,729600

%N Sequence A255412 sorted into ascending order, with duplicates removed.

%C Numbers n such that n = A000203(j) = A000203(k) and A007947(j) = A007947(k), where j != k.

%C In other words, numbers n such that sigma(x) = n has at least two distinct solutions, with each x having the same squarefree kernel, where sigma(x) is the sum of divisor function (A000203).

%C Equally, sequence A000203(A255335(n)) sorted into ascending order, with duplicates removed.

%F a(n) = A000203(A255334(n)) = A000203(A255335(n)) for n = 1 .. 7. - _Antti Karttunen_, Apr 05 2015

%e 4800 is the sum of divisors of 1512 and 2058, and rad(1512) = rad(2058) = 42, hence 4800 is in the sequence with j=1512 and k=2058.

%Y Subsequence of A159886.

%Y Cf. A000203 (sum of divisors of n), A007947 (squarefree kernel of n).

%Y Cf. A254791 (a subsequence).

%Y Cf. A252997, A255334, A255335, A255412.

%K nonn

%O 1,1

%A _Naohiro Nomoto_, Jan 23 2015

%E More terms from _Antti Karttunen_, Apr 13 2015