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A256994
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a(n) = n + 1 when n <= 3, otherwise a(n) = 2^(n-2) + 3; also iterates of A005187 starting from a(1) = 2.
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5
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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
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OFFSET
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1,1
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COMMENTS
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Note that if we instead iterated function b(n) = 1+A005187(n), from b(1) onward, we would get the powers of two, A000079.
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LINKS
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FORMULA
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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)).
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MATHEMATICA
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Table[If[n<4, n+1, 2^(n-2)+3], {n, 40}] (* Harvey P. Dale, May 14 2019 *)
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PROG
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(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)
;; The following uses memoization-macro definec:
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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