A181789 Pandigital biperiod squares: pandigital squares whose digits repeat twice in order.
183673469387755102041183673469387755102041, 326530612244897959184326530612244897959184, 734693877551020408164734693877551020408164, 132231404958677685950413223140496132231404958677685950413223140496
Offset: 1
References
- R. Ondrejka, Problem 1130: Biperiod Squares, Journal of Recreational Mathematics, Vol. 14:4 (1981-82), 299. Solution by F. H. Kierstead, Jr., JRM, Vol. 15:4 (1982-83), 311-312.
Links
- Chai Wah Wu, Table of n, a(n) for n = 1..34
Programs
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Python
from itertools import count, islice from sympy import sqrt_mod def A181789_gen(): # generator of terms for j in count(9): b = 10**j a = b*10+1 for k in sorted(sqrt_mod(0,a,all_roots=True)): if a*b <= (m:=k**2) < a*(a-1) and len(set(str(m//a))) == 10: yield m A181789_list = list(islice(A181789_gen(),20)) # Chai Wah Wu, Mar 23 2024
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