A330908 a(n+1) = a(n) + (number of divisors of a(n) that are not divisors of other divisors of a(n)) for n>1; a(1)=1.
1, 2, 4, 6, 9, 11, 13, 15, 18, 21, 24, 27, 29, 31, 33, 36, 39, 42, 46, 49, 51, 54, 57, 60, 64, 66, 70, 74, 77, 80, 83, 85, 88, 91, 94, 97, 99, 102, 106, 109, 111, 114, 118, 121, 123, 126, 130, 134, 137, 139, 141, 144, 147, 150, 154, 158, 161, 164, 167, 169
Offset: 1
Keywords
Examples
For n = 2 calculate a(2)= a(2-1) + A083399(a(2-1))= 1 + 1 = 2; For n = 3 a(3)=a(2) + A083399(a(2))= 2 + 2 = 4; For n = 4 a(4)=a(3) + A083399(a(3))= 4 + 2 = 6; For n = 5 a(5)=a(4) + A083399(a(4))= 6 + 3 = 9;
Links
- Samuel Frankmartin-Sebastian Wiethüchter, Table of n, a(n) for n = 1..5000
Crossrefs
Cf. A094222.
Programs
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Maple
A330908 := proc(n) option remember; if n < 2 then n else procname(n-1)+A083399(procname(n-1)) end if; end proc: seq(A330908(n), n=1..30);
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Mathematica
a[1] = 1; a[n_] := a[n] = a[n - 1] + PrimeNu[a[n - 1]] + 1; Array[a, 60] (* Amiram Eldar, May 01 2020 *)
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PARI
f(n) = omega(n) + 1; \\ A083399 lista(nn) = {my(a=1, va = List(a)); for (n=2, nn, a = a+f(a); listput(va, a);); Vec(va);} \\ Michel Marcus, May 03 2020
Formula
a(n) = a(n-1) + A083399(a(n-1)) for n>1.
Comments