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A062739 Odd powerful numbers. 3
1, 9, 25, 27, 49, 81, 121, 125, 169, 225, 243, 289, 343, 361, 441, 529, 625, 675, 729, 841, 961, 1089, 1125, 1225, 1323, 1331, 1369, 1521, 1681, 1849, 2025, 2187, 2197, 2209, 2401, 2601, 2809, 3025, 3087, 3125, 3249, 3267, 3375, 3481, 3721, 3969, 4225 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Smallest term of this sequence not also in A075109 is 675, followed by 1125. - Alonso del Arte, Nov 22 2011

REFERENCES

R. K. Guy, Unsolved Problems in Number Theory, B16

LINKS

Zak Seidov, Table of n, a(n) for n = 1..10000

W. A. Sentance, Occurrences of consecutive odd powerful numbers, Amer. Math. Monthly, 88 (1981), 272-274.

FORMULA

It is not true that a(n) = A001694(2n-1).

EXAMPLE

Consecutive-odd examples from Sentance: {25,27},{70225,70227},{189750625,189750627}

MATHEMATICA

Powerful[n_Integer] := (n ==1) || Min[Transpose[FactorInteger[n]][[2]]]>=2; Select[Range[5000], OddQ[ # ]&&Powerful[ # ]&] (* T. D. Noe, May 04 2006 *)

CROSSREFS

Cf. A001694, A060355, A060859, A060860.

Cf. A076445 (consecutive odd powerful numbers).

Sequence in context: A020210 A275196 A325373 * A075109 A319165 A319152

Adjacent sequences:  A062736 A062737 A062738 * A062740 A062741 A062742

KEYWORD

nonn

AUTHOR

Labos Elemer, Jul 12 2001

EXTENSIONS

Checked by T. D. Noe, May 04 2006

STATUS

approved

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Last modified October 21 11:33 EDT 2019. Contains 328296 sequences. (Running on oeis4.)