This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A181055 Numbers n such that sum_{k=1..n} (-1)^(n-k) *bigomega(k) is prime. 0
 4, 6, 8, 10, 12, 24, 26, 28, 30, 32, 34, 46, 52, 70, 78, 82, 102, 126, 128, 132, 134, 136, 138, 168, 186, 190, 192, 222, 234, 274, 280, 312, 316, 322, 336, 378, 418, 424, 426, 440, 472, 484, 492, 504, 532, 540, 558, 570, 574, 584, 592, 602, 604, 606, 650, 652 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS The partial alternating sum over bigomega(.)=A001222(.) in the definition starts at n=1 as 0, 1, 0, 2, -1, 3, -2, 5, -3, 5, -4, 7, -6, 8 ... The first primes in this signed sequence are 2, 3, 5, 5, 7, 17, 17, 17, 19, 23, 23, 31, 37, 53, 59, 61, 79, 97, 103, 107, 107, 107, 109,... occurring at positions 4, 6, 8, 10 etc, which define the sequence. LINKS EXAMPLE 6 is in the sequence because sum_{k=1..6}(-1)^ (6-k)*bigomega(k) = ((-1)^5)*0 + ((-1)^4)*1 + ((-1)^3)*1 + ((-1)^2)*2 + ((-1)^1)*1 + ((-1)^0)*2 = 0 + 1 -1 + 2 -1 + 2 = 3 is prime. MAPLE with(numtheory):for n from 1 to 1000 do: s:=0: for k from 1 to n do :s:=s+((-1)^(n-k))*bigomega(k):od: if type(s, prime)=true then printf(`%d, `, n):else fi:od: CROSSREFS Cf. A001222. Sequence in context: A131694 A053012 A096160 * A225506 A073669 A073670 Adjacent sequences:  A181052 A181053 A181054 * A181056 A181057 A181058 KEYWORD nonn AUTHOR Michel Lagneau, Oct 01 2010 EXTENSIONS Comment slightly extended - R. J. Mathar, Oct 03 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 October 22 04:25 EDT 2019. Contains 328315 sequences. (Running on oeis4.)