login
This site is supported by donations to The OEIS Foundation.
Logo

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A085718 Numbers n such that sopfr(n)/spf(n) is a semiprime and sopfr(n)/lpf(n) is a semiprime, where sopfr(n) = A001414(n) is sum of primes dividing n (with repetition), spf(n) and lpf(n) are smallest and largest primes dividing n, respectively. Also, spf(n)!=lpf(n). 0
72, 576, 648, 750, 800, 900, 960, 1080, 3430, 4116, 4900, 5880, 6272, 7000, 7056, 7938, 8400, 8960, 9450, 10080, 10752, 11340, 12096, 13608, 18750, 20000, 22500, 24000, 25600, 27000, 28800, 30375, 30720, 32400, 34560, 36450, 36864, 37268 (list; graph; refs; listen; history; internal format)
OFFSET

1,1

EXAMPLE

648=2^3*3^4 is a term because 2+2+2+3+3+3+3 = 18 and 18/2 = 9 and 18/3 = 6.

CROSSREFS

Sequence in context: A164377 A156632 A204484 * A205329 A077120 A200451

Adjacent sequences:  A085715 A085716 A085717 * A085719 A085720 A085721

KEYWORD

nonn

AUTHOR

Jason Earls (zevi_35711(AT)yahoo.com), Jul 19 2003

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Transforms | Puzzles | Hot | Classics
Recent Additions | More pages | Superseeker | Maintained by The OEIS Foundation Inc.

Content is available under The OEIS End-User License Agreement .

Last modified February 16 19:20 EST 2012. Contains 205945 sequences.