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A343981
a(n) is the least integer h such that there exists a Pythagorean triple whose hypotenuse is h and whose other legs z satisfy A176774(z) = n.
1
35, 0, 13, 0, 2727, 104, 13911, 17370, 426996, 1855, 340119, 89375, 3588, 37400, 3034, 57709, 2103750, 88400, 53290, 506817, 15263560, 141921, 660350, 3372270, 419356, 40716, 57526469, 356025, 639135, 5316785, 872934, 1493219, 11939849, 119616, 331290, 3008185
OFFSET
3,1
COMMENTS
a(4)=0 is conjectured.
a(6)=0 because all hexagonal numbers are triangular numbers (see A176948).
LINKS
EXAMPLE
a(3)=35 because of [21, 28, 35] where A176774(21) = A176774(35) = 3.
a(5)=13 because of [5, 12, 13] where A176774(5) = A176774(12) = 5.
a(7)=2727 because of [540, 2673, 2727] where A176774(540) = A176774(2673) = 7.
PROG
(PARI) p(s, n) = ((s-2)*n^2 - (s-4)*n)/2;
lista(nn, n) = {my(v = vector(nn, k, p(n, k))); v = select(x->(tp(x)==n), v); my(kh = oo, kv = oo); for (i=1, #v, for (j=1, i, my(h2 = v[i]^2 + v[j]^2, h); if (issquare(h2, &h), if (h < kh, kh = h; kv = [v[j], v[i], kh]); ); ); ); kh; }
a(n) = {if (n==4, return (0)); if (n==6, return (0)); my(nn = 2); while ((res=lista(nn, n)) == oo, nn *= 2); res; }
CROSSREFS
Sequence in context: A067156 A365894 A291452 * A174593 A104785 A225313
KEYWORD
nonn
AUTHOR
Michel Marcus, May 06 2021
STATUS
approved