A069560 -id:A069560 - cp's OEIS frontend

A069557 Squares in which the k-th significant digit either divides k or is a multiple of k. Is 1 only in case k has no other single-digit divisor.

1, 4, 9, 25, 49, 64, 81, 324, 361, 625, 961, 4624, 8649, 7354944

Offset: 1

Amarnath Murthy, Mar 22 2002

If the smallest prime divisor of n is > 7 only in such case the n-th digit is 1.
a(15) > 10^25 if it exists. - David A. Corneth, May 05 2024
The definition implies that no digit can be zero. - N. J. A. Sloane, May 05 2024

			8649 is a member in which the fourth digit is 8, a multiple of 4, the third one is 6, a multiple of 3, the second one is 4, a multiple of 2 and the least significant digit is 9.

David A. Corneth, PARI program

Cf. A052041, A069556, A069560.

okQ[n_]:=Module[{idn=IntegerDigits[n]}, Count[idn,0]==0 && And@@Divisible[idn,Range[Length[idn],1,-1]]]; Select[Range[500]^2, okQ]  (* Harvey P. Dale, Dec 20 2010 *)

PARI
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More terms from Sascha Kurz, Mar 23 2002

Offset corrected and a(14) from Sean A. Irvine, May 04 2024

cp's OEIS Frontend

A069557 Squares in which the k-th significant digit either divides k or is a multiple of k. Is 1 only in case k has no other single-digit divisor.

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