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A240475 Primes that are midway between the closest flanking squarefree numbers. 6
2, 17, 19, 53, 89, 163, 197, 199, 233, 251, 269, 271, 293, 307, 337, 379, 449, 487, 491, 521, 557, 593, 631, 701, 739, 751, 809, 811, 881, 883, 919, 953, 991, 1013, 1049, 1061, 1063, 1097, 1151, 1171, 1279, 1459, 1471, 1493, 1531, 1549, 1567, 1601, 1637 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
Primes for which the corresponding A240473(m) is equal to A240474(m).
Primes equal to the average of the closest flanking squarefree numbers.
Primes equal to the average of three consecutive squarefree numbers.
Most terms are such that a(n)+2 and a(n)-2 are the closest squarefree numbers. The first term > 2 for which this is not the case is a(880) = 47527.
494501773, 765921647, 930996623 are the terms < 10^9 that also belong to A176141.
LINKS
EXAMPLE
19 is a term because it is midway between the closest flanking squarefree numbers 17 and 21.
On the other hand, 29 is not a term because it is not midway between the closest flanking squarefree numbers 26 and 30.
PROG
(PARI) forprime(p=1, 1650, forstep(j=p-1, 1, -1, if(issquarefree(j), L=j; break)); for(j=p+1, 2*p, if(issquarefree(j), G=j; break)); if(G-p==p-L, print1(p", ")))
CROSSREFS
Sequence in context: A042925 A019413 A040138 * A107139 A042055 A075683
KEYWORD
nonn
AUTHOR
Chris Boyd, Apr 06 2014
STATUS
approved

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Last modified March 29 07:27 EDT 2024. Contains 371265 sequences. (Running on oeis4.)