A339597 When 2*n+1 first appears in A086799.

1, 2, 5, 4, 9, 10, 13, 8, 17, 18, 21, 20, 25, 26, 29, 16, 33, 34, 37, 36, 41, 42, 45, 40, 49, 50, 53, 52, 57, 58, 61, 32, 65, 66, 69, 68, 73, 74, 77, 72, 81, 82, 85, 84, 89, 90, 93, 80, 97, 98, 101, 100, 105, 106, 109, 104, 113, 114, 117, 116, 121, 122, 125, 64, 129, 130, 133, 132, 137

Offset: 0

Author

Marc LeBrun and N. J. A. Sloane, Jan 06 2021

Keywords

• nonn
• easy

Links

• Michel Marcus, Table of n, a(n) for n = 0..10000
• Christian Krause, LODA program

Crossrefs

Cf. A086799, A091072 (terms sorted), A129760.

Programs

Maple

N := 127: # for a(0) to a(N)
V := Array(0..N): count := 0:
for i from 1 while count < N+1 do
  with(MmaTranslator[Mma]):
  f(i) := BitOr(i,i-1);
  v := (f(i)-1)/2;
  if v <= N and V[v] = 0 then count := count+1; V[v] := i fi
od:
convert(V,list); # Robert Israel, Jan 07 2021

PARI

f(n) = bitor(n, n-1); \\ A086799
a(n) = my(k=1); while (f(k) != 2*n+1, k++); k; \\ Michel Marcus, Jan 07 2021

PARI

a(n) = n++; n<<1 - 1<Kevin Ryde, Mar 29 2021

Python

def A339597(n): return ((m:=n+1)<<1)-(m&-m) # Chai Wah Wu, Sep 01 2023

Formula

a(n) = 2*(n+1) - A006519(n+1) = n+1 with a 0 bit inserted above its least significant 1-bit. - Kevin Ryde, Mar 29 2021

a(n) = A129760(n+1) + n+1. - Christian Krause, May 05 2021