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A136478 Smallest y such that for x = A136477(n), x^2 + x + y^2 is an odd primitive abundant number, A136476(n). 3
7, 7, 3, 15, 15, 15, 7, 3, 5, 7, 3, 15, 15, 27, 3, 15, 3, 27, 15, 27, 13, 3, 49, 17, 55, 27, 27, 15, 53, 77, 63, 77, 15, 45, 15, 69, 45, 77, 15, 57, 75, 27, 75, 63, 55, 75, 49, 85, 7, 3 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
See A136477 and A136476 for the x-values and the abundant numbers x^2 + x + y^2.
LINKS
FORMULA
a(n) = sqrt(A136476(n) - A136477(n)^2 - A136477(n)). - M. F. Hasler, Feb 22 2017
EXAMPLE
97^2+97+7^2 = 9555 = A136476(1) is an odd primitive abundant number, therefore a(1) = 7.
PROG
(PARI) {for(x=1, 5000, my(n=x^2+x+1, f); forstep(y=1, sqrtint(2*x), 2, sigma(n+=y*4-4, -1)>2 || next; for(i=1, #f=factor(n)[, 1], sigma(n\f[i], -1)>2 && next(2)); print1(y", "); break))} \\ M. F. Hasler, Feb 22 2017
CROSSREFS
Sequence in context: A220052 A153204 A199508 * A097903 A221566 A064619
KEYWORD
nonn
AUTHOR
Pierre CAMI, Dec 31 2007
EXTENSIONS
Edited by M. F. Hasler, Feb 22 2017
STATUS
approved

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Last modified March 18 22:56 EDT 2024. Contains 370952 sequences. (Running on oeis4.)