A269928 Integers n that belong to more Pythagorean triples than preceding integers.

1, 3, 5, 12, 15, 24, 40, 48, 60, 120, 240, 360, 420, 720, 840, 1560, 1680, 2520, 3360, 5040, 8400, 9240, 10920, 15120, 18480, 21840, 27720, 32760, 36960, 43680, 55440, 65520, 109200, 110880, 120120, 166320, 196560, 221760, 240240, 360360, 480480, 720720, 1113840

Offset

1,2

Comments

Called optimal P-numbers in Tripathi link.

Links

Table of n, a(n) for n=1..43.

A. Tripathi, On Pythagorean triples containing a fixed integer, Fib. Q., 46/47 (2008/2009), 331-340. See Theorem 11.

Index entries related to Pythagorean Triples.

Prog

(PARI) nbpt(n) = {oddn = n/(2^valuation(n, 2)); f = factor(oddn); for (k=1, #f~, if ((f[k, 1] % 4) != 1, f[k, 2] = 0); ); n1 = factorback(f); if (n % 2, (numdiv(n^2)+numdiv(n1^2))/2 -1, (numdiv((n/2)^2)+numdiv(n1^2))/2 -1); }
lista(nn) = {last = -1; for (n=1, nn, if ((new = nbpt(n)) > last, print1(n, ", "); last = new; ); ); }

Crossrefs

Cf. A046081, A269929.

Sequence in context: A080560 A260818 A151866 * A057587 A213036 A032438

Adjacent sequences: A269925 A269926 A269927 * A269929 A269930 A269931

Keyword

nonn

Author

Michel Marcus, Mar 08 2016

Status

approved