A290303 Values of usigma(n) = usigma(n+1).

24, 60, 72, 180, 1440, 2160, 1872, 2640, 2400, 3000, 2880, 3024, 4320, 4320, 4320, 5280, 5280, 7400, 8640, 10080, 10200, 11520, 11880, 11520, 11088, 12960, 12096, 14400, 25920, 21600, 26640, 34560, 25200, 40320, 34560, 36000, 51840, 60480, 63360, 60480, 65280

Offset

1,1

Comments

The sum of unitary divisors of numbers n such that n and n+1 have the same sum.

The unitary version of A053215.

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000

Formula

a(n) = A034448(A064125(n)).

Mathematica

usigma[n_] := Block[{d = Divisors[n]}, Plus @@ Select[d, GCD[ #, n/# ] == 1 &]]; a={}; u1=0; For[k=0, k<10^5, k++; u2=usigma[k]; If[u1==u2, a = AppendTo[a, u1]]; u1=u2]; a

Crossrefs

Cf. A002961, A034448, A053215, A064125.

Sequence in context: A190104 A255968 A211325 * A044126 A044507 A101860

Adjacent sequences: A290300 A290301 A290302 * A290304 A290305 A290306

Keyword

nonn

Author

Amiram Eldar, Jul 26 2017

Status

approved