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

Thanks to everyone who made a donation during our annual appeal!
To see the list of donors, or make a donation, see the OEIS Foundation home page.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A183100 a(n) = sum of divisors d of n which are either 1 or of the form Product_(i) (p_i^e_i) where the e_i are <= 1. 4
 1, 3, 4, 3, 6, 12, 8, 3, 4, 18, 12, 24, 14, 24, 24, 3, 18, 30, 20, 38, 32, 36, 24, 48, 6, 42, 4, 52, 30, 72, 32, 3, 48, 54, 48, 42, 38, 60, 56, 78, 42, 96, 44, 80, 69, 72, 48, 96, 8, 68, 72, 94, 54, 84, 72, 108, 80, 90, 60, 164, 62, 96, 95, 3, 84, 144, 68, 122, 96, 144, 72, 66, 74, 114, 99, 136, 96, 168, 80, 158, 4, 126, 84, 220, 108, 132, 120, 168, 90, 225, 112, 164, 128, 144, 120, 192, 98, 122, 147, 88 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS a(n) = sum of non-powerful divisors d of n where powerful numbers are numbers from A001694(m) for m >=1. LINKS Antti Karttunen, Table of n, a(n) for n = 1..16385 FORMULA a(n) = A000203(n) - A183099(n) = A183098(n) + 1. a(1) = 1, a(p) = p+1, a(pq) = (p+1)*(q+1), a(pq...z) = (p+1)*(q+1)*…*(z+1), a(p^k) = p+1, for p, q = primes, k = natural numbers, pq...z = product of k (k > 2) distinct primes p, q, ..., z. EXAMPLE For n = 12, set of such divisors is {1, 2, 3, 6, 12}; a(12) = 1+2+3+6+12 = 24. PROG (PARI) A183100(n) = (1 + sumdiv(n, d, d*(!ispowerful(d)))); \\ Antti Karttunen, Oct 07 2017 CROSSREFS Cf. A000203, A001694, A183098, A183099. Sequence in context: A048250 A323363 A073181 * A046897 A109506 A000113 Adjacent sequences:  A183097 A183098 A183099 * A183101 A183102 A183103 KEYWORD nonn AUTHOR Jaroslav Krizek, Dec 25 2010 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 January 21 10:26 EST 2020. Contains 331105 sequences. (Running on oeis4.)