a(1) = 1; for n>1, a(n) = the smallest prime divisor of the number C(n) formed from the reverse concatenation of 1,2,3,... up to n.

A075020

a(1) = 1; for n>1, a(n) = the smallest prime divisor of the number C(n) formed from the reverse concatenation of 1,2,3,... up to n.

Terms

    a(0) =1a(1) =3a(2) =3a(3) =29a(4) =3a(5) =3a(6) =19a(7) =3a(8) =3a(9) =7a(10) =3a(11) =3a(12) =17a(13) =3a(14) =3a(15) =23a(16) =3a(17) =3a(18) =17a(19) =3a(20) =3a(21) =13a(22) =3a(23) =3a(24) =11a(25) =3a(26) =3a(27) =23a(28) =3a(29) =3

External references