

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
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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



