A084004 Squares obtained as a concatenation of k and 10's complement of k.

64, 7921, 9604, 164836, 351649, 996004, 19758025, 20647936, 29757025, 30846916, 97990201, 99960004, 1203187969, 1975180249, 3086469136, 4265657344, 8143618564, 9999600004, 115644884356, 131504868496, 132231867769, 140039859961, 173879826121, 339900660100, 391600608400

Offset: 1

Author

Amarnath Murthy, May 23 2003

Keywords

• base
• nonn

Links

• Andrew Howroyd, Table of n, a(n) for n = 1..65

Crossrefs

Cf. A084005, A084006, A084007.

Programs

PARI

b(n)={my(k=logint(n,10)+1); (n+1)*10^k - n}
{ for(k=1, 10^6, my(x=b(k)); if(issquare(x), print1(x, ", "))) } \\ Andrew Howroyd, Sep 22 2024

Formula

a(n) = A084005(n)^2. - Andrew Howroyd, Sep 21 2024

Extensions

More terms from Ray Chandler, May 31 2003

Offset changed and a(22) onwards from Andrew Howroyd, Sep 21 2024