This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A061228 a(1) = 2, a(n) = smallest number greater than n which is not coprime to n. 17
 2, 4, 6, 6, 10, 8, 14, 10, 12, 12, 22, 14, 26, 16, 18, 18, 34, 20, 38, 22, 24, 24, 46, 26, 30, 28, 30, 30, 58, 32, 62, 34, 36, 36, 40, 38, 74, 40, 42, 42, 82, 44, 86, 46, 48, 48, 94, 50, 56, 52, 54, 54, 106, 56, 60, 58, 60, 60, 118, 62, 122, 64, 66, 66, 70, 68, 134, 70, 72, 72 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Reinhard Zumkeller, Table of n, a(n) for n = 1..10000 FORMULA a(2m) = 2m+2, a(p)= 2p if p is a prime. a(n)= n + the smallest divisor (more than 1) of n. a(p^k) = p^k + p if p is prime. - Robert Israel, Oct 21 2015 EXAMPLE a(9) = 12 as 10 and 11 are coprime to 9. a(11) = 22 as 11 is a prime. MAPLE for n from 1 to 150 do if n=1 then printf(`%d, `, 2); fi: for k from n+1 to 2*n do if igcd(n, k)>1 then printf(`%d, `, k); break; fi: od: od: # alternative: 2, seq(t + min(numtheory:-factorset(t)), t = 2..1000); # Robert Israel, Oct 21 2015 MATHEMATICA Table[n+First@(First/@FactorInteger[n]), {n, 200}] (* Vladimir Joseph Stephan Orlovsky, Apr 08 2011 *) PROG (Haskell) a061228 n = n + a020639 n  -- Reinhard Zumkeller, May 06 2015 CROSSREFS Cf. A046666, A064413. Equals A020639(n) + n. Cf. A070229, A256393. Sequence in context: A056942 A115947 A247653 * A070229 A248835 A053568 Adjacent sequences:  A061225 A061226 A061227 * A061229 A061230 A061231 KEYWORD nonn AUTHOR Amarnath Murthy, Apr 23 2001 EXTENSIONS More terms from James A. Sellers, Apr 24 2001 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 August 20 14:06 EDT 2019. Contains 326152 sequences. (Running on oeis4.)