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A180425 Number of positive integers below 10^n requiring 3 positive squares in their representation as sum of squares. 4
2, 42, 505, 5586, 59308, 616995, 6347878, 64875490, 660104281, 6695709182, 67762820595, 684596704482, 6907026402474, 69611115440126, 700946070114283, 7053023642205904 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..16.

Eric W. Weisstein, MathWorld -- Lagrange's Four-Square Theorem.

Eric W. Weisstein, MathWorld -- Sum of Squares Function.

FORMULA

a(n) = #{k: A000419(k) < 10^n}.

A049416(n) + A180416(n) + a(n) + A167615(n) = A002283(n).

CROSSREFS

Cf. A000419, A049416, A180416, A167615, A002283.

Sequence in context: A070808 A229474 A157056 * A140170 A318247 A038396

Adjacent sequences:  A180422 A180423 A180424 * A180426 A180427 A180428

KEYWORD

nonn,more

AUTHOR

Martin Renner, Jan 19 2011

EXTENSIONS

a(6)=616995 by Lars Blomberg, May 03 2011

a(7)-a(10) from Donovan Johnson, Jul 01 2011

a(10) corrected and a(11)-a(16) from Hiroaki Yamanouchi, Jul 13 2014

STATUS

approved

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Last modified April 19 05:26 EDT 2021. Contains 343105 sequences. (Running on oeis4.)