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Search: id:A008935
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| A008935 |
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If 2n = Sum 2^e(k) then a(n) = Sum e(k)^2. |
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+0
2
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| 1, 4, 5, 9, 10, 13, 14, 16, 17, 20, 21, 25, 26, 29, 30, 25, 26, 29, 30, 34, 35, 38, 39, 41, 42, 45, 46, 50, 51, 54, 55, 36, 37, 40, 41, 45, 46, 49, 50, 52, 53, 56, 57, 61, 62, 65, 66, 61, 62, 65, 66, 70, 71, 74, 75, 77, 78, 81, 82, 86, 87, 90, 91, 49, 50, 53, 54, 58, 59, 62
(list; graph; listen)
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OFFSET
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1,2
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LINKS
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T. D. Noe, Table of n, a(n) for n=1..1023
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FORMULA
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G.f. 1/(1-x) * sum(k>=0, (k+1)^2*x^2^k/(1+x^2^k)). - Ralf Stephan (ralf(AT)ark.in-berlin.de), Jun 23 2003
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EXAMPLE
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To get a(5), we write 10 = 2+8 = 2^1 + 2^3 so a(5) = 1^2+3^2 = 10.
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PROGRAM
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(C): #include <stdio.h> #include <stdlib.h> #define USAGE "Usage: 'A008935 num'\n where num is the index of the desired ending value in the sequence.\n" #define MAX 1023 #define SHIFT_MAX 9
int main(int argc, char *argv[]) { unsigned short mask, i, j, end; unsigned long sum; if (argc < 2) { fprintf(stderr, USAGE); return EXIT_FAILURE; } end = atoi(argv[1]); end = (end >= MAX) ? MAX : end;
fprintf(stdout, "Values: "); for (i = 1; i <= end; i++) { sum = 0; mask = 1; for (j = 0; j < SHIFT_MAX; j++, mask *= 2) if (i & mask) sum += (j+1) * (j+1); fprintf(stdout, "%ld", sum); if (i < end) fprintf(stdout, ", "); } fprintf(stdout, "\n"); return EXIT_SUCCESS; }
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CROSSREFS
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Gives A003995 if sorted and duplicates removed.
Sequence in context: A007536 A064801 A109825 this_sequence A003995 A064473 A001983
Adjacent sequences: A008932 A008933 A008934 this_sequence A008936 A008937 A008938
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KEYWORD
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nonn,nice,easy
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AUTHOR
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njas
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EXTENSIONS
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Corrected and extended by Larry Reeves (larryr(AT)acm.org), Mar 22 2000
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