The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A196228 Number of ways of writing n as sum of a prime and a perfect power. 3
 0, 0, 1, 1, 0, 2, 1, 1, 1, 1, 3, 2, 1, 2, 2, 1, 1, 2, 2, 2, 3, 1, 2, 1, 1, 1, 4, 2, 2, 3, 1, 4, 2, 2, 3, 1, 2, 5, 4, 2, 2, 2, 2, 3, 4, 2, 3, 2, 3, 2, 4, 2, 2, 3, 3, 4, 2, 1, 2, 2, 2, 4, 3, 1, 2, 3, 3, 5, 4, 2, 2, 3, 2, 2, 5, 1, 4, 2, 3, 4, 2, 1, 5, 3, 1, 4, 4 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,6 COMMENTS In this case, perfect power does not include 0. Different from A133364. The first difference is at n=74, where a(n) = 2 but A133364(n) = 3. LINKS T. D. Noe, Table of n, a(n) for n = 1..10000 FORMULA a(n) = Card_{n=i+j where i is in A000040 and j is in A001597}. G.f.: (Sum_{k>=1} x^prime(k))*(Sum_{k = i^j, i>=1, j>=2} x^k). - Ilya Gutkovskiy, Feb 18 2017 EXAMPLE a(1) = a(2) = a(5) = a(1549) = a(1771561) = 0, see A119748. MATHEMATICA nn = 100; pwrs = Union[{1}, Flatten[Table[Range[2, Floor[nn^(1/ex)]]^ex, {ex, 2, Floor[Log[2, nn]]}]]]; pp = Prime[Range[PrimePi[nn]]]; t = Table[0, {nn}]; Do[ t[[i[[1]]]] = i[[2]], {i, Tally[Sort[Select[Flatten[Outer[Plus, pwrs, pp]], # <= nn &]]]}]; t (* T. D. Noe, Sep 29 2011 *) CROSSREFS Cf. A119748 (zero terms). Cf. A000040, A001597, A133364. Sequence in context: A212171 A337255 A337375 * A133364 A063420 A347917 Adjacent sequences:  A196225 A196226 A196227 * A196229 A196230 A196231 KEYWORD easy,nonn AUTHOR Philippe Deléham, Sep 29 2011 EXTENSIONS Edited by Franklin T. Adams-Watters, Sep 29 2011 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified June 26 18:18 EDT 2022. Contains 354885 sequences. (Running on oeis4.)