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

0,2

Links

Michel Marcus, Table of n, a(n) for n = 0..10000

Christian Krause, LODA program

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

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

Prog

(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<<valuation(n, 2); \\ Kevin Ryde, Mar 29 2021
(Python)
def A339597(n): return ((m:=n+1)<<1)-(m&-m) # Chai Wah Wu, Sep 01 2023

Crossrefs

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

Sequence in context: A204923 A123302 A227368 * A368736 A120119 A364035

Adjacent sequences: A339594 A339595 A339596 * A339598 A339599 A339600

Keyword

nonn,easy

Author

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

Status

approved