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

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A337853 a(n) is the number of partitions of n as the sum of two Niven numbers. 3
 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 5, 5, 5, 4, 4, 3, 3, 3, 3, 3, 4, 3, 4, 4, 4, 4, 5, 4, 5, 4, 4, 4, 3, 2, 4, 3, 3, 4, 3, 3, 5, 3, 4, 5, 4, 4, 7, 4, 5, 6, 5, 3, 7, 4, 4, 6, 4, 2, 7, 3, 4, 5, 4, 3, 7, 3, 4, 5, 4, 3, 8, 3, 4, 6, 3, 3, 6, 2, 5, 6, 5, 3, 8, 4, 4, 6 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,5 COMMENTS a(n) >= 1 for n >= 2 ?. For n <= 200000, a(n) = 1 only for n = 2, 3, 299, (2 = 1 + 1, 3 = 1 + 2, 299 = 1 + 288) and a(n) = 2 only for n in {4, 5, 35, 59, 79, 95, 97, 149, 169, 179, 389}. LINKS Rémy Sigrist, Table of n, a(n) for n = 0..10000 EXAMPLE 0 and 1 cannot be decomposed as the sum of two Niven numbers, so a(0) = a(1) = 0. 4 = 1 + 3 = 2 + 2 and 1, 2, 3 are in A005349, so a(4) = 2. 15 = 3 + 12 = 5 + 10 = 6 + 9 = 7 + 8 and 3, 5, 6, 7, 8, 9, 10, 12 are in A005349, so a(15) = 4. MATHEMATICA m = 100; nivens = Select[Range[m], Divisible[#, Plus @@ IntegerDigits[#]] &]; a[n_] := Length[IntegerPartitions[n, {2}, nivens]]; Array[a, m, 0] (* Amiram Eldar, Sep 27 2020 *) PROG (Magma) niven:=func; [#RestrictedPartitions(n, 2, {k: k in [1..n-1] | niven(k)}): n in [0..100]]; CROSSREFS Cf. A005349, A116357, A172151, A172398, A180149, A280829, A319468, A302479, A319395, A337854. Sequence in context: A341721 A290323 A260254 * A282711 A035100 A303594 Adjacent sequences: A337850 A337851 A337852 * A337854 A337855 A337856 KEYWORD nonn,base AUTHOR Marius A. Burtea, Sep 26 2020 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 August 11 10:58 EDT 2024. Contains 375068 sequences. (Running on oeis4.)