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A294393
a(n) is the smallest number whose deficiency or abundance is equal to 2*n (or 0 if such a number does not exist), minus the n-th odd number.
2
5, 0, 0, 0, 13, 0, 0, 12, 0, 0, 25, 0, 87, 31, 0, 0, 217, 22, 0, 16, 0, 0, 49, 0, 11, 55, 0, 32, 27, 0, 0, 22, 43, 0, 73, 0, 0, 637, 81, 0, 75, 0, 320, 28, 0, 50, 313, 24, 0, 103, 0, 0, 109, 0, 0, 34, 0, 62, 301, 24, -1, 120, 67, 0, 133, 0, 128, 139, 0, 0, 433, 42, 23, 151, 0, 0, 219, 82, 0, 28, 119
OFFSET
0,1
COMMENTS
Note that a(60) = -1.
FORMULA
a(n) = A294386(n) - A005408(n).
EXAMPLE
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n A294386(n) - A005408(n) = a(n)
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0 6 1 5
1 3 3 0
2 5 5 0
3 7 7 0
4 22 9 13
...
PROG
(PARI) f(n) = abs(2*n-sigma(n));
a(n) = my(k=1); while(f(k) != 2*n, k++); k - (2*n+1); \\ Michel Marcus, Oct 31 2017
KEYWORD
sign
AUTHOR
Omar E. Pol, Oct 30 2017
STATUS
approved