A030287 a(n) is the smallest k > a(n-1) such that k^2 has no digit in common with a(n-1)^2.

0, 1, 2, 3, 4, 5, 6, 7, 9, 15, 19, 20, 23, 26, 29, 30, 34, 47, 56, 65, 83, 85, 90, 156, 241, 264, 265, 291, 300, 334, 448, 563, 638, 715, 780, 961, 2000, 2261, 2457, 3335, 5478, 7154, 9128, 9569, 14220, 17654, 20000, 22609, 26462, 28604, 30000

Offset: 0

Author

Patrick De Geest

Keywords

• nonn
• base

Comments

a(n) = sqrt(A030288(n)). - Zak Seidov, Feb 20 2009

Links

• David W. Wilson, Table of n, a(n) for n = 0..231

Crossrefs

Cf. A030288: squares whose digits do not appear in previous term.

Cf. A067581: a(n) has no digit of a(n-1).

See also A294660.

Programs

Mathematica

Nest[Append[#, Block[{k = Last[#] + 1}, While[IntersectingQ @@ IntegerDigits@ {Last[#]^2, k^2}, k++]; k]] &, {0}, 50] (* Michael De Vlieger, Nov 03 2017 *)

PARI

next_A030287(n,D=Set(digits(n^2)))=for(k=n+1,oo,#setintersect(Set(digits(k^2)),D)||return(k))
print1(a=0);for(i=1,99,print1(","a=next_A030287(a))) \\ M. F. Hasler, Nov 08 2017

Extensions

Edited by N. J. A. Sloane, Feb 22 2009 at the suggestion of R. J. Mathar