a(n) is the unique even-valued residue modulo 5^n of a number m such that m^2+1 is divisible by 5^n.

A258929

a(n) is the unique even-valued residue modulo 5^n of a number m such that m^2+1 is divisible by 5^n.

Terms

    a(0) =2a(1) =18a(2) =68a(3) =182a(4) =1068a(5) =1068a(6) =32318a(7) =280182a(8) =280182a(9) =3626068a(10) =23157318a(11) =120813568a(12) =1097376068a(13) =1097376068a(14) =11109655182a(15) =49925501068a(16) =355101282318a(17) =355101282318

External references