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A185584 Positive numbers equal to the sum of the squares of their first k divisors for some k. 6

%I

%S 1,130,1860,148480,3039520,4172437680,5788838100,38341734200,

%T 41251514850,54116036100,78936002964,1059758860356

%N Positive numbers equal to the sum of the squares of their first k divisors for some k.

%C 676358763167556, 3238006053537840, 343869932366333100, 408390181577292600, 466477390306128600 and 5447947283895097800 are also terms. - _Donovan Johnson_, Jan 20 2014

%e 130 --> (1, 2, 5, 10): 1^2+2^2+5^2+10^2 = 1+4+25+100 = 130.

%e 1860 --> (1, 2, 3, 4, 5, 6, 10, 12, 15, 20, 30).

%e 148480 --> (1, 2, 4, 5, 8, 10, 16, 20, 29, 32, 40, 58, 64, 80, 116, 128, 145, 160, 232).

%e 3039520 --> (1, 2, 4, 5, 8, 10, 11, 16, 20, 22, 32, 40, 44, 55, 80, 88, 110, 121, 157, 160, 176, 220, 242, 314, 352, 440, 484, 605, 628, 785, 880).

%t Select[Range[5000000],MemberQ[Accumulate[Divisors[#]^2],#]&] [From Harvey P. Dale]

%o (PARI) isA185584(n) = fordiv(n,d,(n-=d^2)<0&return;n|return(1))

%o for(n=1,1e7,isA185584(n)&print1(n", ")) \\ _M. F. Hasler_

%Y Cf. A064510.

%Y See A185873 for the values of k.

%K nonn,more

%O 1,2

%A _Claudio Meller_, Feb 04 2011

%E a(6) from _Charles R Greathouse IV_, Feb 05 2011

%E a(7) from _Donovan Johnson_, Feb 05 2011

%E Edited by _N. J. A. Sloane_, Feb 05 2011

%E a(8)-a(11) from _Donovan Johnson_, Feb 07 2011

%E a(12) from _Donovan Johnson_, Jan 20 2014

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Last modified August 24 16:16 EDT 2019. Contains 326295 sequences. (Running on oeis4.)