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A016032 Least number that is the sum of two positive squares in exactly n ways. 19
2, 50, 325, 1105, 8125, 5525, 105625, 27625, 71825, 138125, 5281250, 160225, 1221025, 2442050, 1795625, 801125, 446265625, 2082925, 41259765625, 4005625, 44890625, 30525625, 61051250, 5928325, 303460625, 53955078125, 35409725, 100140625, 1289367675781250 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

REFERENCES

A. Beiler, Recreations in the Theory of Numbers, Dover, pp. 140-141.

LINKS

T. D. Noe and Ray Chandler, Table of n, a(n) for n = 1..2178 (a(2179) exceeds 1000 digits).

C. Rivera, Puzzle 62

Eric Weisstein's World of Mathematics, Square Number

G. Xiao, Two squares

Index entries for sequences related to sums of squares

FORMULA

a(n) = min(2*A018782(2n-1), A018782(2n), A018782(2n+1)).

EXAMPLE

a(1) = 2 from 2 = 1^2 + 1^2.

a(2) = 50 from 50 = 1^2 + 7^2 = 5^2 + 5^2.

CROSSREFS

Cf. A048610, A025284-A025293 (first entries).

See A000446, A124980 and A093195  for other versions.

Sequence in context: A226337 A048610 A007511 * A080299 A083939 A083941

Adjacent sequences:  A016029 A016030 A016031 * A016033 A016034 A016035

KEYWORD

nonn,nice

AUTHOR

Robert G. Wilson v

EXTENSIONS

Corrected and extended by Jud McCranie

Definition improved by several correspondents, Nov 12 2007

STATUS

approved

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Last modified April 30 08:33 EDT 2017. Contains 285645 sequences.