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URL: https://oeis.org/A078930

⇱ A078930 - OEIS

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A078930
Let r+i*s be the sum of the distinct first-quadrant Gaussian integers dividing n; sequence gives r+s values.
4
1, 5, 4, 13, 12, 20, 8, 29, 13, 56, 12, 52, 24, 40, 48, 61, 28, 65, 20, 144, 32, 60, 24, 116, 81, 112, 40, 104, 44, 224, 32, 125, 48, 136, 96, 169, 52, 100, 96, 320, 60, 160, 44, 156, 156, 120, 48, 244, 57, 369, 112, 288, 72, 200, 144, 232, 80, 212, 60, 576, 84, 160, 104
OFFSET
1,2
COMMENTS
Also equal to the sum of all divisors of n (in Z[i]) having positive real part. - M. F. Hasler, Nov 22 2007
FORMULA
a(n) = A078910(n) + A078911(n) (while A078910(n) - A078911(n) = A000203(n)).
a(n) = A000203(n) + 2*A078911(n). - M. F. Hasler, Nov 22 2007
PROG
(PARI) A078930(n, S=[])=sigma(n)+sumdiv(n*I, d, if(real(d)&imag(d)&!setsearch(S, d=vecsort(abs([real(d), imag(d)]))), S=setunion(S, [d]); (d[1]+d[2])<<(d[1]!=d[2]))) \\ M. F. Hasler, Nov 22 2007
CROSSREFS
Sequence in context: A226555 A147685 A353151 * A381993 A329162 A383096
KEYWORD
nonn
AUTHOR
Vladeta Jovovic, Jan 11 2003
STATUS
approved