login
A168270
Squarefree numbers which are also isolated numbers.
0
2, 6, 23, 30, 37, 42, 47, 53, 67, 79, 83, 89, 97, 102, 113, 127, 131, 138, 157, 163, 167, 173, 211, 223, 233, 251, 257, 263, 277, 282, 293, 307, 317, 331, 337, 353, 359, 367, 373, 379, 383, 389, 397, 401, 409, 439, 443, 449, 457, 462, 467, 479, 487, 491, 499, 503, 509
OFFSET
1,1
FORMULA
A005117 INTERSECT A167706.
MAPLE
isA007510 := proc(n) if isprime(n) then not isprime(n-2) and not isprime(n+2) ; else false; end if ; end proc:
isA014574 := proc(n) isprime(n+1) and isprime(n-1) ; end proc:
isA167706 := proc(n) isA007510(n) or isA014574(n) ; end proc:
isA005117 := proc(n) n =1 or numtheory[issqrfree](n) ; end proc:
isA168270 := proc(n) isA005117(n) and isA167706(n) ; end proc:
for n from 1 to 600 do if isA168270(n) then printf("%d, ", n) ; fi; od: # R. J. Mathar, Dec 09 2009
CROSSREFS
KEYWORD
nonn
AUTHOR
EXTENSIONS
Corrected (missing terms inserted) by R. J. Mathar, Dec 09 2009
STATUS
approved