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A256994 a(n) = n + 1 when n <= 3, otherwise a(n) = 2^(n-2) + 3; also iterates of A005187 starting from a(1) = 2. 5
2, 3, 4, 7, 11, 19, 35, 67, 131, 259, 515, 1027, 2051, 4099, 8195, 16387, 32771, 65539, 131075, 262147, 524291, 1048579, 2097155, 4194307, 8388611, 16777219, 33554435, 67108867, 134217731, 268435459, 536870915, 1073741827, 2147483651, 4294967299, 8589934595, 17179869187, 34359738371, 68719476739, 137438953475, 274877906947 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
Note that if we instead iterated function b(n) = 1+A005187(n), from b(1) onward, we would get the powers of two, A000079.
LINKS
FORMULA
If n < 4, a(n) = n + 1, otherwise a(n) = 2^(n-2) + 3 = A062709(n-2).
a(1) = 2; for n > 1, a(n) = A005187(a(n-1)).
MATHEMATICA
Table[If[n<4, n+1, 2^(n-2)+3], {n, 40}] (* Harvey P. Dale, May 14 2019 *)
PROG
(PARI)
A256994(n) = if(n < 4, n+1, 2^(n-2) + 3);
\\ Alternatively, by iterating A005187:
A005187(n) = { my(s=n); while(n>>=1, s+=n); s; };
i=1; k=2; print1(k); while(i <= 40, k = A005187(k); print1(", ", k); i++);
(Scheme, two alternatives)
(define (A256994 n) (if (< n 4) (+ n 1) (+ (A000079 (- n 2)) 3)))
;; The following uses memoization-macro definec:
(definec (A256994 n) (if (= 1 n) 2 (A005187 (A256994 (- n 1)))))
CROSSREFS
Topmost row of A256995, leftmost column of A256997.
Sequence in context: A327010 A341823 A339548 * A107481 A058521 A116628
KEYWORD
nonn
AUTHOR
Antti Karttunen, Apr 15 2015
STATUS
approved

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Last modified March 28 18:04 EDT 2024. Contains 371254 sequences. (Running on oeis4.)