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A232748
Partial sums of the characteristic function of Hofstadter's A030124.
4
0, 1, 1, 2, 3, 4, 4, 5, 6, 7, 8, 8, 9, 10, 11, 12, 13, 13, 14, 15, 16, 17, 18, 19, 20, 20, 21, 22, 23, 24, 25, 26, 27, 28, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59
OFFSET
1,4
COMMENTS
Useful for computing A232749.
FORMULA
a(1)=0, and for n>1, a(n) = A232748(n-1) + (1-(A232746(n)-A232746(n-1))).
MATHEMATICA
nmax = 100; A5228 = {1}; Module[{d = 2, k = 1}, Do[While[MemberQ[A5228, d], d++]; k += d; d++; AppendTo[A5228, k], {n, 1, nmax}]];
a46[n_] := For[k = 1, True, k++, If[A5228[[k]] > n, Return[k-1]]];
a[n_] := a[n] = If[n == 1, 0, a[n-1] + (1 - (a46[n] - a46[n-1]))];
Array[a, nmax] (* Jean-François Alcover, Dec 09 2021 *)
PROG
(Scheme, with memoization macro definec from Antti Karttunen's IntSeq-library)
(definec (A232748 n) (cond ((< n 2) (- n 1)) (else (+ (A232748 (- n 1)) (- 1 (- (A232746 n) (A232746 (- n 1))))))))
CROSSREFS
KEYWORD
nonn
AUTHOR
Antti Karttunen, Nov 30 2013
STATUS
approved