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

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A054251 a(0) = 1; a(n) = Sum_{0 <= k < n and gcd(k, n) != 1} a(k). 2
 1, 0, 1, 1, 2, 1, 5, 1, 9, 7, 19, 1, 45, 1, 83, 79, 165, 1, 417, 1, 827, 639, 1575, 1, 3875, 927, 7025, 5069, 14689, 1, 35461, 1, 64199, 47175, 128399, 52727, 309767, 1, 566565, 409567, 1186863, 1, 2835257, 1, 5202425, 4888729, 10357675, 1, 26066615 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,5 LINKS G. C. Greubel, Table of n, a(n) for n = 0..1000 MATHEMATICA a[0]:= 1; a[n_]:= a[n] =Sum[If[GCD[k, n]!=1, a[k], 0], {k, 0, n-1}]; Table[a[n], {n, 0, 50}] (* G. C. Greubel, Jul 31 2019 *) PROG (PARI) a(n) = if(n==0, 1, sum(j=0, n-1, if(gcd(j, n)!=1, a(j), 0))); vector(50, n, n--; a(n)) \\ G. C. Greubel, Jul 31 2019 CROSSREFS Cf. A045545. Sequence in context: A093127 A115123 A132081 * A163963 A119763 A092142 Adjacent sequences:  A054248 A054249 A054250 * A054252 A054253 A054254 KEYWORD nonn AUTHOR 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 8 02:45 EDT 2020. Contains 336290 sequences. (Running on oeis4.)