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 A280642 Numbers k such that k^3 has an odd number of digits and the middle digit is 2. 3
 5, 9, 103, 113, 133, 146, 151, 154, 165, 180, 198, 202, 470, 473, 493, 496, 504, 507, 521, 531, 538, 542, 566, 569, 581, 591, 593, 599, 612, 618, 620, 650, 654, 673, 681, 686, 703, 711, 715, 728, 729, 732, 740, 779, 801, 829, 841, 850, 855, 856, 857, 858, 874 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS The sequence of cubes starts: 125, 729, 1092727, 1442897, 2352637, 3112136, 3442951, 3652264, ... LINKS Lars Blomberg, Table of n, a(n) for n = 1..10000 Jeremy Gardiner, Middle digit in cube numbers, Seqfan Mailing list, Dec 12 2016. EXAMPLE 5^3 = 1(2)5, 180^3 = 583(2)000, 618^3 = 2360(2)9032. MATHEMATICA a[n_]:=Part[IntegerDigits[n], (Length[IntegerDigits[n]]+1)/2]; Select[Range[0, 874], OddQ[Length[IntegerDigits[#^3]]] && a[#^3]==2 &] (* Indranil Ghosh, Mar 06 2017 *) PROG (PARI) isok(k) = my(d=digits(k^3)); (#d%2 == 1) && (d[#d\2 +1] == 2); for(k=0, 874, if(isok(k)==1, print1(k, ", "))); \\ Indranil Ghosh, Mar 06 2017 (Python) i=0 j=1 while i<=874:     n=str(i**3)     l=len(n)     if l%2 and n[(l-1)//2]=="2":         print(str(i), end=', ')         j+=1     i+=1 # Indranil Ghosh, Mar 06 2017 CROSSREFS Cf. A280640-A280641, A280643-A280649, A181354. See A279420-A279429 for a k^2 version. See A279430-A279431 for a k^2 version in base 2. Sequence in context: A098097 A279707 A329002 * A222583 A222374 A097397 Adjacent sequences:  A280639 A280640 A280641 * A280643 A280644 A280645 KEYWORD nonn,base,easy,changed AUTHOR Lars Blomberg, Jan 07 2017 STATUS approved

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Last modified May 7 19:23 EDT 2021. Contains 343652 sequences. (Running on oeis4.)