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A074491 "Squarefree" primes: primes without squares in their decimal expansion. 0
2, 3, 5, 7, 23, 37, 53, 67, 73, 83, 223, 227, 233, 263, 277, 283, 337, 353, 373, 383, 523, 557, 563, 577, 587, 653, 673, 677, 683, 727, 733, 757, 773, 787, 823, 827, 853, 857, 863, 877, 883, 887, 2237, 2267, 2273, 2287, 2333, 2357, 2377, 2383, 2633, 2657 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

The usual definition of "squarefree number" means that there is no square as a factor of the number, but we consider "squarefree numbers" as those without any square in its decimal expansion (or representation). The procedure "omit numbers with squares in their decimal expansion" is rather severe: from 500 first primes only 68 survive and are in the sequence, while all primes are squarefree in usual sense!

LINKS

Table of n, a(n) for n=1..52.

EXAMPLE

3557 is a member because it has no squares 0, 1, 4, 9, 16, 25, 36 in its decimal expansion; 3253 is a prime but contains the square 25 so it is not a member.

CROSSREFS

Cf. A059307.

Sequence in context: A113611 A038925 A154761 * A154385 A125525 A019546

Adjacent sequences:  A074488 A074489 A074490 * A074492 A074493 A074494

KEYWORD

easy,nonn,base

AUTHOR

Zak Seidov, Sep 26 2002

STATUS

approved

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Last modified April 17 20:01 EDT 2014. Contains 240655 sequences.