A330821 a(1) = 1, a(2) = 2. Thereafter a(n+1) is the smallest number k such that A001414(k) = a(n) + a(n-1).

1, 2, 3, 5, 15, 51, 305, 1059, 4083, 117737, 3775459, 19465955, 952896293, 13613071346, 14565967639, 112716155924, 11073544747197, 637616871476643, 11027737075804991, 3056322734187753262, 542921033413649799807, 8189660342217563295915, 515222301162241572644117

Offset

1,2

Links

Jinyuan Wang, Table of n, a(n) for n = 1..200

Formula

a(n+1) = A056240(a(n) + a(n-1)).

Example

sopfr(3) = 3 = 2 + 1, sopfr(15) = 8 = 3 + 5, etc.

Mathematica

s[1] = 0; s[n_] := Plus @@ Times @@@ FactorInteger@n; a[1] = 1; a[2] = 2; a[n_] := a[n] = Module[{k = 1, sum = a[n - 1] + a[n - 2]}, While[s[k] != sum, k++]; k]; Array[a, 10] (* Amiram Eldar, Jan 02 2020 *)

Crossrefs

Cf. A000045, A001414, A056240.

Sequence in context: A227633 A270011 A111183 * A248827 A273525 A377853

Adjacent sequences: A330818 A330819 A330820 * A330822 A330823 A330824

Keyword

nonn

Author

David James Sycamore, Jan 02 2020

Extensions

Data corrected by and more terms from Amiram Eldar and David A. Corneth, Jan 02 2020

Data corrected by Jinyuan Wang, Mar 08 2020

Status

approved