A116509 Values of c in a^2 + b^2 = c^2 where b - a = 31 and gcd(a,b)=1.

41, 109, 221, 629, 1285, 3665, 7489, 21361, 43649, 124501, 254405, 725645, 1482781, 4229369, 8642281, 24650569, 50370905, 143674045, 293583149, 837393701, 1711127989, 4880688161, 9973184785, 28446735265, 58127980721

Offset

1,1

Comments

b - a = 31 is the fifth term of A058529

Links

Table of n, a(n) for n=1..25.

Formula

c(1)=41,c(2)=109,c(3)=221,c(4)=629,c(n)=6*c(n-2)-c(n-4)

Example

c(5)= 6*221-41=1285 and 893^2 + 924^2 = 1285^2 and 924-893=31 and gcd(893,924)=1

Mathematica

RecurrenceTable[{a[1]==41, a[2]==109, a[3]==221, a[4]==629, a[n]==6a[n-2]-a[n-4]}, a, {n, 30}] (* Harvey P. Dale, Aug 01 2021 *)

Crossrefs

Sequence in context: A279213 A070270 A001125 * A105389 A266954 A290589

Adjacent sequences: A116506 A116507 A116508 * A116510 A116511 A116512

Keyword

nonn

Author

Andras Erszegi (erszegi.andras(AT)chello.hu), Mar 21 2006

Status

approved