A181585 "Early bird" squares: write the square numbers in a string 149162536496481100... . Sequence gives numbers k such that k^2 occurs in the string ahead of its natural place.

7, 8, 21, 25, 46, 97, 129, 161, 196, 221, 245, 258, 277, 296, 350, 436, 460, 592, 661, 694, 789, 804, 875, 877, 1250, 2025, 2221, 3500, 3959, 4020, 5461, 5920, 7925, 9607, 12500, 14772, 19821, 20010, 21825, 22011, 22221, 24012, 25225, 25375, 25388, 26013, 28014

Offset

1,1

Comments

Corresponding positions of the k^2's in a string 149162536496481100... are 2, 9, 23, 5, 112, 209, 395, 336, 496, 465, 656, 935, 65, 486, 603, 75, 112, 1115, 2317, 3163, 2329, 1987, 252, 421, 4036, 4279, 7092, ... .

Links

Michael S. Branicky, Table of n, a(n) for n = 1..145

Mathematica

s="1"; ss={}; Do[tsn=ToString[n^2]; If[ !StringFreeQ[s, tsn], AppendTo[ss, n]; Print[n]]; s=s<>tsn, {n, 2, 99999}];

Prog

(Python)
def aupto(limit):
    s, alst = "", []
    for k in range(1, limit+1):
        ss = str(k*k)
        if ss in s: alst.append(k)
        s += ss
    return alst
print(aupto(28028)) # Michael S. Branicky, Jul 08 2021

Crossrefs

Cf. A000290, A116700, A141817.

Sequence in context: A309482 A308926 A152043 * A060291 A132899 A051175

Adjacent sequences: A181582 A181583 A181584 * A181586 A181587 A181588

Keyword

base,nonn

Author

Zak Seidov, Oct 31 2010

Extensions

a(46) and beyond from Michael S. Branicky, Jul 08 2021

Status

approved