login
A206027
a(n) = the number of solutions to sigma(x) = A145899(n).
4
1, 2, 3, 5, 6, 7, 8, 9, 10, 11, 15, 21, 29, 35, 37, 49, 58, 59, 68, 79, 98, 111, 160, 224, 256, 317, 382, 426, 431, 563, 576, 624, 774, 865, 883, 1050, 1195, 1265, 1371, 1376, 1742, 1755, 1935, 2095, 2437, 2447, 2944, 3055, 3318, 3324, 3366, 4289, 4369, 4502
OFFSET
1,2
LINKS
FORMULA
a(n) = A054973(A145899(n)). - Michel Marcus, Oct 22 2013
EXAMPLE
a(4) = 5 because the 5 numbers x such that sigma(x) = A145899(4) = 72 are x = 30, 46, 51, 55, 71.
MATHEMATICA
t = DivisorSigma[1, Range[10^6]]; t2 = Sort[Tally[t]]; mn = 0; t3 = {}; Do[If[t2[[n]][[2]] > mn, mn = t2[[n]][[2]]; AppendTo[t3, t2[[n]][[2]]]], {n, Length[t2]}]; t3 (* T. D. Noe, Feb 03 2012 *)
CROSSREFS
Cf. A000203 (sigma = sum of divisors of n), A145899, A206026.
Sequence in context: A264387 A282843 A074137 * A039222 A340745 A183295
KEYWORD
nonn
AUTHOR
Jaroslav Krizek, Feb 03 2012
EXTENSIONS
Extended to 1376 by T. D. Noe, Feb 04 2012
Terms a(41) and beyond from Donovan Johnson, Feb 04 2012
STATUS
approved