Tribonacci

Compute the nth Tribonacci number.

The Tribonacci numbers are the integer sequence

0 comma 0 comma 1 comma 1 comma 2 comma 4 comma 7 comma 13 comma 24 comma 44 comma 81 comma 149 comma 274 comma 504 comma 927 comma 1705 comma ellipsis

The sequence is defined by the recurrence relation

upper F Subscript n Baseline equals upper F Subscript n minus 1 Baseline plus upper F Subscript n minus 2 Baseline plus upper F Subscript n minus 3

with seed values F_0 = 0, F_1 = 0, and F_2 = 1.

Usage

var tribonacci = require( '@stdlib/math/base/special/tribonacci' );

tribonacci( n )

Computes the nth Tribonacci number.

var v = tribonacci( 0 );
// returns 0

v = tribonacci( 1 );
// returns 0

v = tribonacci( 2 );
// returns 1

v = tribonacci( 3 );
// returns 1

v = tribonacci( 63 );
// returns 8607945812375585

If n > 63, the function returns NaN, as larger Tribonacci numbers cannot be safely represented in double-precision floating-point format.

var v = tribonacci( 64 );
// returns NaN

If not provided a nonnegative integer value, the function returns NaN.

var v = tribonacci( 3.14 );
// returns NaN

v = tribonacci( -1 );
// returns NaN

If provided NaN, the function returns NaN.

var v = tribonacci( NaN );
// returns NaN

Examples

var tribonacci = require( '@stdlib/math/base/special/tribonacci' );

var v;
var i;

for ( i = 0; i < 64; i++ ) {
    v = tribonacci( i );
    console.log( v );
}
Did you find this page helpful?