The OEIS is supported by the many generous donors to the OEIS Foundation.

 Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 59th year, we have over 358,000 sequences, and we’ve crossed 10,300 citations (which often say “discovered thanks to the OEIS”). Other ways to Give
 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A050934 Numbers n such that phi(n)*d(n) is a multiple of sigma(n), where d(n) is the number of divisors of n. 0
 1, 3, 14, 35, 42, 105, 209, 248, 297, 418, 594, 627, 744, 1045, 1254, 1485, 1736, 2926, 3135, 3339, 3596, 3689, 3956, 4064, 4158, 5208, 5396, 5890, 6461, 7315, 7668, 8370, 8636, 8680, 8778, 8932, 9875, 10013, 10395, 10788, 11067, 11687 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Equality holds for 1, 3, 14, 42 and no others < 4290000000. LINKS EXAMPLE phi(35)*d(35)=4*24, a multiple of sigma(35)=48, so 35 is in the sequence. MATHEMATICA Select[Range[12000], Divisible[EulerPhi[#]DivisorSigma[0, #], DivisorSigma[ 1, #]]&] (* Harvey P. Dale, Jan 11 2019 *) CROSSREFS Cf. A000005, A000010, A000203. Sequence in context: A076533 A081379 A081377 * A110427 A296294 A128916 Adjacent sequences: A050931 A050932 A050933 * A050935 A050936 A050937 KEYWORD nonn AUTHOR Jud McCranie, Dec 30 1999 STATUS approved

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

Last modified December 5 12:01 EST 2022. Contains 358586 sequences. (Running on oeis4.)