A058425
Numbers k such that k^2 contains only digits {0,2,5}, not ending with zero.
Original entry on oeis.org
5, 15, 45, 235, 505, 745, 1415, 1485, 4495, 5005, 15985, 50005, 72495, 469255, 500005, 500505, 1597505, 1598515, 4474955, 5000005, 5000505, 5050005, 7085235, 15008515, 44949995, 50000005, 50000505, 50005005, 50500005, 500000005, 500000505, 500005005, 500254955, 500500005
Offset: 1
A119051
Triangular numbers composed of digits {0,2,5}.
Original entry on oeis.org
55, 5050, 25200, 255255, 500500, 50005000, 525220255, 2250500505, 5000050000, 22052205055, 500000500000, 520022025225, 2205022050055, 2225205025200, 5220005220550, 50000005000000, 220500220500055, 550250022200005, 2552552000225055, 5000000050000000
Offset: 1
Original entry on oeis.org
25, 27, 32, 225, 2025, 2197, 2500, 3025, 3375, 7225, 11025, 13225, 21952, 22500, 27000, 27225, 55225, 70225, 112225, 133225, 172225, 195112, 202500, 207025, 235225, 250000, 255025, 302500, 319225, 511225, 555025, 570025, 722500, 1102500, 1113025, 1177225, 1311025
Offset: 1
32 is a term since A329147(21) = 32 = 2^5.
2197 is a term since A329147(194) = 2197 = 13^3.
235225 is a term since A329147(123113) = 235225 = 485^2.
Subsequences of squares with specified digits:
A058426 (0,2,5),
A053919 (2,3,5),
A030485 (2,5,7),
A191486 (2,3,5,7).
-
p[n_] := If[n > 0, Prime[n], 0]; ppQ[n_] := GCD @@ FactorInteger[n][[;; , 2]] > 1; seq[ndigmax_] := Module[{t = Table[FromDigits[Flatten@ IntegerDigits@ (p /@ IntegerDigits[n])], {n, 0, 10^ndigmax - 1}]}, Union@ Select[t, 0 < # < 10^ndigmax && ppQ[#] &]]; seq[6] (* Amiram Eldar, Mar 26 2023 *)
-
f(n) = if (n, fromdigits(concat(apply(d -> if (d, digits(prime(d)), [0]), digits(n)))), 0); \\ A329147
lista(nn) = my(list = List(), m); for (n=0, nn, m = f(n); if ((m <= nn) && ispower(m), listput(list, m));); vecsort(Set(list)); \\ Michel Marcus, Mar 26 2023
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