33 lines
454 B
C
33 lines
454 B
C
#include <stdio.h>
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// Sum of Arithmetic Sequence
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// an = a1 + (n-1) * d
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// Sn = (a1 + an) * n/2
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int main(void) {
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int d, a1, n, an, Sn;
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printf("Sum of Arithmetic Sequence!\n");
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printf("a1:");
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scanf("%d", &a1);
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printf("d:");
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scanf("%d", &d);
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printf("n:");
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scanf("%d", &n);
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//an = a1 + (n-1) * d;
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//Sn = (a1 + an) * n/2;
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Sn = (a1 + (a1+(n-1)*d) ) * n/2;
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printf("Sn := %d\n", Sn);
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return 0;
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}
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