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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 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 September 17 11:16 EDT 2021. Contains 347478 sequences. (Running on oeis4.)