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 A125302 Nonprime numbers n such that n cannot be a semiperimeter of an integer Heronian triangle. 0
 1, 4, 10, 14, 26, 46, 51, 58, 62, 69, 74, 92, 94, 106, 122, 123, 141, 142, 158, 188, 202, 206, 213, 218, 254, 267, 284, 298, 302, 314, 329, 334, 339, 346, 355, 362, 365, 382, 394, 398, 411, 446, 458, 478, 485, 501, 526, 538, 542, 554, 573, 586, 622, 634, 668 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Trivially, no prime number can be a semiperimeter of an integer Heronian triangle. Therefore primes are excluded from the sequence. LINKS Table of n, a(n) for n=1..55. Eric Weisstein's World of Mathematics, Heronian Triangle. MAPLE notriangle:=proc(n::nonnegint) local a, b, c; if type(n, prime) then RETURN(false) fi; for a from floor(2*n/3) to n-1 do for b from floor(n-a/2) to a do c:=2*n-a-b; if type(sqrt(n*(n-a)*(n-b)*(n-c)), integer) then RETURN(false); fi; od; od; RETURN(true); end: N:=100: a:=array[1..N]: i:=0: n:=0: while i

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Last modified July 14 16:43 EDT 2024. Contains 374322 sequences. (Running on oeis4.)