A155985 a(1)=1, then a(n) is the smallest square not occurring earlier, not ending with zero and starting with the last digit of a(n-1).
1, 16, 64, 4, 49, 9, 961, 121, 144, 441, 169, 9025, 529, 9216, 625, 576, 676, 6084, 484, 4096, 6241, 196, 6561, 1024, 4225, 5041, 1089, 9409, 9604, 4356, 6724, 4489, 9801, 1156, 6889, 90601, 1225, 5184, 4624, 4761, 1296, 60025, 5329, 91204, 40401, 1369
Offset: 1
Links
- David A. Corneth, Table of n, a(n) for n = 1..10000
- David A. Corneth, PARI program
Programs
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PARI
nxt(va, d) = {my(k=1); while ((digits(k^2)[1]!=d) || !(k%10) || #select(x->(x==k^2), va), k++); k^2;} lista(nn) = {my(va = vector(nn)); va[1] = 1; for (n=2, nn, va[n] = nxt(va, Vecrev(digits(va[n-1]))[1]);); va;} \\ Michel Marcus, Sep 04 2020 -
PARI
\\ See Corneth link. David A. Corneth, Sep 05 2020
Extensions
Name edited by Michel Marcus, Sep 04 2020