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!)
A323069 Number of divisors d of n such that A049820(d) > 1 and A049820(d) is also a divisor of n. 3
0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 2, 0, 0, 1, 1, 0, 2, 0, 0, 0, 0, 0, 3, 0, 0, 0, 0, 0, 3, 0, 1, 0, 0, 1, 4, 0, 0, 0, 1, 0, 1, 0, 0, 1, 0, 0, 4, 0, 0, 0, 0, 0, 2, 0, 1, 0, 0, 0, 4, 0, 0, 0, 1, 0, 1, 0, 0, 0, 2, 0, 5, 0, 0, 1, 0, 0, 1, 0, 1, 0, 0, 0, 2, 0, 0, 0, 1, 0, 4, 0, 0, 0, 0, 0, 4, 0, 0, 1, 0, 0, 1, 0, 1, 2 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,12

LINKS

Antti Karttunen, Table of n, a(n) for n = 1..10080

FORMULA

Sum_{d|n} [A049820(d) > 1 and A049820(d)|n], where [ ] is the Iverson bracket.

a(n) <= A323068(n).

a(n) >= A322358(n).

PROG

(PARI) A323069(n) = sumdiv(n, d, my(t=(d-numdiv(d))); ((t>1)&&!(n%t)));

CROSSREFS

Cf. A000005, A049820, A322358, A323068.

Sequence in context: A161369 A151843 A276422 * A325334 A280287 A147696

Adjacent sequences:  A323066 A323067 A323068 * A323070 A323071 A323072

KEYWORD

nonn

AUTHOR

Antti Karttunen, Jan 05 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 27 12:30 EDT 2020. Contains 337380 sequences. (Running on oeis4.)