login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A324708 Lesser of tri-unitary amicable numbers pair: numbers (m, n) such that tsigma(m) = tsigma(n) = m + n, where tsigma(n) is the sum of the tri-unitary divisors of n (A324706). 4
114, 594, 1140, 5940, 8640, 10744, 12285, 13500, 44772, 60858, 62100, 67095, 67158, 79296, 79650, 79750, 118500, 142310, 143808, 177750, 185368, 298188, 308220, 356408, 377784, 462330, 545238, 600392, 608580, 609928, 624184, 635624, 643336, 643776, 669900 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

The larger counterparts are in A324709.

LINKS

Table of n, a(n) for n=1..35.

EXAMPLE

114 is in the sequence since it is the lesser of the amicable pair (114, 126): tsigma(114) = tsigma(126) = 114 + 126.

MATHEMATICA

f[p_, e_] := If[e == 3, (p^4-1)/(p-1), If[e==6, (p^8-1)/(p^2-1), p^e+1]]; tsigma[1]=1; tsigma[n_]:= Times @@ f @@@ FactorInteger[n]; s[n_] := tsigma[n] - n; seq={}; Do[m=s[n]; If[m>n && s[m]==n, AppendTo[seq, n]] , {n, 1, 700000}]; seq

CROSSREFS

Cf. A002025, A002952, A126169, A292980, A322541, A324706, A324707, A324709.

Sequence in context: A251475 A292980 A126169 * A251459 A251452 A239570

Adjacent sequences:  A324705 A324706 A324707 * A324709 A324710 A324711

KEYWORD

nonn

AUTHOR

Amiram Eldar, Mar 11 2019

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified September 18 12:35 EDT 2021. Contains 347527 sequences. (Running on oeis4.)