A366473 a(1) = 1; thereafter a(n) = A337136(n) + A337136(n-1).

1, 3, 5, 8, 9, 10, 14, 15, 16, 19, 29, 48, 41, 53, 94, 67, 81, 82, 31, 47, 78, 60, 31, 80, 82, 42, 43, 64, 67, 158, 160, 51, 42, 44, 38, 39, 58, 62, 66, 67, 234, 237, 75, 74, 72, 75, 78, 82, 86, 90, 91, 94, 97, 145, 147, 101, 152, 153, 106, 110, 111, 112, 115, 81, 83, 143, 148, 129, 127, 190, 193, 259, 263, 333, 332, 137, 205, 212, 147, 149, 226, 223, 297

Offset: 1

Author

N. J. A. Sloane, Oct 26 2023

Keywords

• nonn

Links

• Michael De Vlieger, Table of n, a(n) for n = 1..10000
• Michael De Vlieger, Log log scatterplot of a(n), n = 1..2^14, accentuating prime powers in red.

Crossrefs

Cf. A337136.

Programs

Mathematica

nn = 120;
  c[_] := False;
  Array[Set[{a[#], c[#]}, {#, True}] &, 2]; Set[{i, j, u},
   Range[3]]; s = i + j;
  Do[k = u;
    While[Or[c[k], CoprimeQ[s, k]], k++];
    Set[{a[n], c[k], i, j, s}, {s, True, j, k, j + k}];
    If[k == u, While[c[u], u++]], {n, 2, nn}];
Array[a, nn] (* Michael De Vlieger, Oct 26 2023 *)