id:A068673 - OEIS Search Results

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Numbers which yield primes when a 1 is prefixed or appended.

+0
5

1, 3, 7, 13, 27, 31, 49, 57, 63, 81, 91, 97, 99, 103, 109, 117, 123, 129, 151, 153, 181, 187, 193, 201, 213, 231, 237, 259, 279, 297, 301, 319, 327, 367, 409, 423, 427, 439, 459, 483, 487, 493, 523, 543, 553, 559, 571, 579, 601, 609, 613, 621, 627, 657, 669 (list; graph; listen)

	OFFSET	`1,2`
	EXAMPLE	`57 is a term as 157 as well as 571 are primes.`
	MAPLE	`i := 0:for k from 1 to 3200 do if(isprime(1+10k) and isprime(k+10^(ceil(evalf(log(k+1)/log(10))))1)) then s[i] := k; i := i+1; end if; end do:q := seq(s[j], j=0..i-1);`
	CROSSREFS	`Adjacent sequences: A068670 A068671 A068672 this_sequence A068674 A068675 A068676` `Sequence in context: A007909 A099810 A125898 this_sequence A140465 A080241 A098479`
	KEYWORD	`base,easy,nonn`
	AUTHOR	`Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Mar 02 2002`
	EXTENSIONS	`More terms from Sascha Kurz (sascha.kurz(AT)uni-bayreuth.de), Mar 17 2002`

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Last modified October 5 16:50 EDT 2008. Contains 144613 sequences.

AT&T Labs Research