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A155139 Primes p such that both p-+3 are not squarefree. 6
47, 53, 101, 239, 347, 353, 487, 547, 647, 653, 683, 719, 853, 947, 953, 1061, 1153, 1213, 1277, 1447, 1453, 1553, 1663, 1669, 1693, 1697, 1747, 1753, 1847, 2053, 2153, 2251, 2347, 2447, 2647, 2659, 2741, 2753, 2887, 2953, 3041, 3253, 3347, 3359, 3433 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
47-3=44=2^2*11, 47+3=50=2*5^2, ...
LINKS
MATHEMATICA
<<NumberTheory`NumberTheoryFunctions` (* needed with older versions *)
lst={}; Do[p=Prime[n]; If[ !SquareFreeQ[p-3]&&!SquareFreeQ[p+3], AppendTo[lst, p]], {n, 6!}]; lst
Select[Prime[Range[500]], !SquareFreeQ[#-3]&&!SquareFreeQ[#+3]&] (* Harvey P. Dale, May 01 2012 *)
PROG
(PARI) lista(nn) = forprime(p=3, nn, if (! issquarefree(p-3) && ! issquarefree(p+3), print1(p, ", "))); \\ Michel Marcus, Jul 05 2016
CROSSREFS
Sequence in context: A128940 A243431 A141279 * A106279 A275022 A355601
KEYWORD
nonn
AUTHOR
STATUS
approved

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Last modified June 21 19:01 EDT 2024. Contains 373557 sequences. (Running on oeis4.)