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A001092 Union of all numbers {p, q} where p and q are both primes or powers of primes and q = p+2. 1
1, 2, 3, 4, 5, 7, 9, 11, 13, 17, 19, 23, 25, 27, 29, 31, 41, 43, 47, 49, 59, 61, 71, 73, 79, 81, 83, 101, 103, 107, 109, 125, 127, 137, 139, 149, 151, 167, 169, 179, 181, 191, 193, 197, 199, 227, 229, 239, 241, 243, 269, 271, 281, 283, 311, 313, 347, 349, 359 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

REFERENCES

M. Abramowitz and I. A. Stegun, eds., Handbook of Mathematical Functions, National Bureau of Standards Applied Math. Series 55, 1964 (and various reprintings), p. 844.

LINKS

T. D. Noe, Table of n, a(n) for n = 1..10000

M. Abramowitz and I. A. Stegun, eds., Handbook of Mathematical Functions, National Bureau of Standards, Applied Math. Series 55, Tenth Printing, 1972 [alternative scanned copy].

PROG

(PARI) {isprimepower(n)=matsize(factor(n))[1]==1} for(n=1, 400, if(isprimepower(n)&&(isprimepower(n-2)||isprimepower(n+2)), print1(n", "))) \\ Ralf Stephan, Aug 20 2004

CROSSREFS

Cf. A053702, A074852.

Sequence in context: A325266 A284288 A074583 * A327782 A000430 A166684

Adjacent sequences:  A001089 A001090 A001091 * A001093 A001094 A001095

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane

EXTENSIONS

Corrected and extended by Larry Reeves (larryr(AT)acm.org), Jun 14 2001

STATUS

approved

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Last modified November 13 23:01 EST 2019. Contains 329106 sequences. (Running on oeis4.)