A079311 - OEIS

A079311

Integer part of length of diagonal of integral rectangle with area n and smallest semiperimeter.

1, 2, 3, 2, 5, 3, 7, 4, 4, 5, 11, 5, 13, 7, 5, 5, 17, 6, 19, 6, 7, 11, 23, 7, 7, 13, 9, 8, 29, 7, 31, 8, 11, 17, 8, 8, 37, 19, 13, 9, 41, 9, 43, 11, 10, 23, 47, 10, 9, 11, 17, 13, 53, 10, 12, 10, 19, 29, 59, 11, 61, 31, 11, 11, 13, 12, 67, 17, 23, 12, 71, 12, 73, 37, 15, 19, 13, 14, 79

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,2

COMMENTS

n <= a(n); for n > 1, a(n)=n iff n is prime.

LINKS

Table of n, a(n) for n=1..79.

FORMULA

a(n) = floor(sqrt(A033676(n)^2 + A033677(n)^2)).

MATHEMATICA

Table[Floor@ Sqrt@ Total@ Map[#^2 &, If[IntegerQ@ #, {#, #}, {Last@ #1, First@ #2} & @@ TakeDrop[#, LengthWhile[#, # <= Sqrt@ n &]] &@ Divisors@ n] &@ Sqrt@ n], {n, 79}] (* Michael De Vlieger, Dec 22 2017 *)

CROSSREFS

Cf. A033676, A033677, A063655.

Sequence in context: A117818 A363627 A073890 * A364391 A060474 A065988

Adjacent sequences: A079308 A079309 A079310 * A079312 A079313 A079314

KEYWORD

nonn

AUTHOR

Reinhard Zumkeller, Feb 11 2003

STATUS

approved