A053919 Squares composed of digits {2,3,5}.

25, 225, 55225, 235225, 3553225, 33235225, 252333225, 2523555225, 3325252225, 5232352225, 3235555525225, 232555332555225, 35232553232323225, 32355552523523552532225, 25532532332552235533223325522255225, 332222523225232223533222222253253255253352335533253225

Offset: 1

Author

Patrick De Geest, Mar 15 2000

Keywords

• nonn
• base

Links

• Patrick De Geest, Squares containing at most three distinct digits, Index entries for related sequences
• Author?, Source(txt)
• H. Mishima Squares consisted of 3 different digits

Crossrefs

Cf. A053918.

Programs

Python

# see link in A053918 for a faster version
from math import isqrt
def aupto(limit):
  alst, rootlimit = [], isqrt(limit)
  for k in range(1, rootlimit+1):
    if set(str(k*k)) <= set("235"): alst.append(k*k)
  return alst
print(aupto(4*10**12)) # Michael S. Branicky, May 15 2021

Formula

a(n) = A053918(n)^2.

Extensions

More terms from C. Ronaldo (aga_new_ac(AT)hotmail.com), Jan 03 2005

One more term from Mishima's webpage added by Max Alekseyev, Jun 17 2011

a(16) from Zhao Hui Du, Feb 29 2024