login
A254035
Sequence A255412 sorted into ascending order, with duplicates removed.
5
4800, 28800, 57600, 67200, 86400, 96000, 115200, 142800, 144000, 148800, 153600, 182400, 201600, 211200, 230400, 259200, 288000, 297600, 326400, 345600, 355200, 384000, 403200, 432000, 470400, 489600, 499200, 518400, 528000, 547200, 576000, 614400, 633600, 638400, 662400, 672000, 691200, 720000, 729600
OFFSET
1,1
COMMENTS
Numbers n such that n = A000203(j) = A000203(k) and A007947(j) = A007947(k), where j != k.
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).
Equally, sequence A000203(A255335(n)) sorted into ascending order, with duplicates removed.
FORMULA
a(n) = A000203(A255334(n)) = A000203(A255335(n)) for n = 1 .. 7. - Antti Karttunen, Apr 05 2015
EXAMPLE
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.
CROSSREFS
Subsequence of A159886.
Cf. A000203 (sum of divisors of n), A007947 (squarefree kernel of n).
Cf. A254791 (a subsequence).
Sequence in context: A096517 A221005 A227495 * A255412 A254791 A096790
KEYWORD
nonn
AUTHOR
Naohiro Nomoto, Jan 23 2015
EXTENSIONS
More terms from Antti Karttunen, Apr 13 2015
STATUS
approved