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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).
2
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
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
KEYWORD
nonn
AUTHOR
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