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A194578 Numbers n such that the sum of the first k divisors of n^2+1 is equal to n for some k. 0
1, 3, 43, 68, 93, 228, 612, 1903, 32292, 44868, 252072, 36564198, 55862807, 134735264 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

No further at least up to 10^7.

No other terms up to 10^8. - Michel Marcus, Jan 17 2014

a(15) > 2.5*10^8. - Giovanni Resta, Apr 14 2017

LINKS

Table of n, a(n) for n=1..14.

EXAMPLE

The divisors of 43^2 + 1 are {1, 2, 5, 10, 25, 37, 50, 74, 185, 370, 925, 1850} and 1+2+5+10 + 25 = 43, hence 43 is in the list.

MATHEMATICA

Select[Range[10000000], MemberQ[Accumulate[Divisors[#^2+1]], #]&]

CROSSREFS

Cf. A185584.

Sequence in context: A253577 A059802 A139854 * A185632 A006033 A246994

Adjacent sequences:  A194575 A194576 A194577 * A194579 A194580 A194581

KEYWORD

nonn

AUTHOR

Michel Lagneau, Aug 29 2011

EXTENSIONS

a(12)-a(13) from Michel Marcus, Jan 17 2014

a(14) from Giovanni Resta, Apr 14 2017

STATUS

approved

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Last modified August 15 00:52 EDT 2020. Contains 336484 sequences. (Running on oeis4.)