This site is supported by donations to The OEIS Foundation.

 Please make a donation to keep the OEIS running. We are now in our 55th year. In the past year we added 12000 new sequences and reached 8000 citations (which often say "discovered thanks to the OEIS"). We need to raise money to hire someone to manage submissions, which would reduce the load on our editors and speed up editing. Other ways to donate

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A060662 Sigma(x) = n has exactly six solutions. 1
 168, 252, 288, 384, 768, 1248, 1584, 1860, 2052, 2480, 2904, 3906, 3968, 4116, 4176, 4224, 4256, 4284, 4392, 4416, 4620, 5824, 5850, 5856, 5928, 6084, 6192, 6216, 6600, 6636, 6660, 6888, 6944, 7104, 7182, 7308, 7840, 7992, 8184, 8976, 9114, 9480, 9856 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Robert Israel, Table of n, a(n) for n = 1..10000 EXAMPLE 168 = sigma(60) = sigma(78) = sigma(92) = sigma(123) = sigma(143) = sigma(167). MAPLE N:= 10^4: # for terms <= N V:= Vector(N): for n from 1 to N-1 do s:= numtheory:-sigma(n); if s <= N then V[s]:= V[s]+1 fi od: select(t -> V[t]=6, [\$1..N]); # Robert Israel, Nov 21 2019 MATHEMATICA a = Table[ 0, {10000} ]; Do[ s = DivisorSigma[ 1, n ]; If[ s < 10001, a[ [ s ] ]++ ], {n, 1, 10000} ]; Select[ Range[ 10000 ], a[ [ # ] ] == 6 & ] CROSSREFS Cf. A007370, A007371, A007372. Sequence in context: A045242 A117529 A196591 * A171256 A059463 A302365 Adjacent sequences:  A060659 A060660 A060661 * A060663 A060664 A060665 KEYWORD nonn AUTHOR Robert G. Wilson v, Apr 18 2001 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.

Last modified December 7 05:14 EST 2019. Contains 329839 sequences. (Running on oeis4.)