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A018930 Define {b(n)} by b(1)=3, b(n) (n >= 2) is smallest number such that b(1)^2+...+b(n)^2 = m^2 for some m and all b(i) are distinct. Sequence gives values of b(n). 5
3, 4, 12, 84, 132, 12324, 1836, 105552, 255084, 197580, 10358340, 13775220, 1936434780, 51299286012, 123205977516, 862441842612, 1310543298204, 667510076211780, 207181940072172, 110912831751840, 1698410314006284 (list; graph; refs; listen; history; internal format)
OFFSET

1,1

MATHEMATICA

f[n_]:=Module[{a={3}}, Do[AppendTo[a, First[y/. {ToRules[Reduce[{y^2+a.a == x^2, x>0, y>0}, {y, x}, Integers]]}]], {n-1}]; a]; f[21]//Timing (* Jean-François Alcover, Jan 26 2007 *)

CROSSREFS

Cf. A018928, A018929.

Sequence in context: A052626 A122903 A059792 * A127689 A127690 A092417

Adjacent sequences:  A018927 A018928 A018929 * A018931 A018932 A018933

KEYWORD

nonn

AUTHOR

Charles Reed, charles.reed(AT)bbs.ewgateway.org

EXTENSIONS

More terms from David W. Wilson (davidwwilson(AT)comcast.net).

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Last modified February 17 23:08 EST 2012. Contains 206085 sequences.