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Search: id:A048853
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| A048853 |
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Number of primes (different from n) that can be produced by altering one digit of decimal expansion of n (without changing the number of digits). |
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+0
23
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| 4, 3, 3, 4, 3, 4, 3, 4, 4, 4, 7, 4, 8, 4, 4, 4, 7, 4, 7, 2, 7, 2, 6, 2, 2, 2, 7, 2, 5, 2, 5, 2, 8, 2, 2, 2, 5, 2, 7, 3, 6, 3, 7, 3, 3, 3, 6, 3, 8, 2, 7, 2, 6, 2, 2, 2, 7, 2, 5, 2, 5, 2, 8, 2, 2, 2, 5, 2, 7, 3, 6, 3, 7, 3, 3, 3, 8, 3, 6, 2, 7, 2, 6, 2, 2, 2, 7, 2, 5, 1, 6, 1, 7, 1, 1, 1, 4, 1, 6, 4, 10, 4, 8, 4, 4
(list; graph; listen)
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OFFSET
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1,1
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EXAMPLE
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Altering the number 13 gives eight primes: 11, 17, 19, 23, 43, 53, 73, 83, so a(13)=8.
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MAPLE
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A048853 := proc(n::integer) local resul, ddigs, d, c, tmp ; resul := 0 ; ddigs := convert(n, base, 10) ; for d from 1 to nops(ddigs) do for c from 0 to 9 do if c = 0 and d = nops(ddigs) then continue ; else if c <> op(d, ddigs) then tmp := [op(1..d-1, ddigs), c, op(d+1..nops(ddigs), ddigs)] ; tst := sum(op(i, tmp)*10^(i-1), i=1..nops(tmp)) ; if isprime(tst) then resul := resul+1 ; fi ; fi ; fi ; od : od ; RETURN(resul) ; end: for n from 1 to 90 do printf("%d, ", A048853(n)) ; od ; - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Apr 25 2006
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CROSSREFS
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Cf. A050652-A050673.
Sequence in context: A059124 A026858 A129344 this_sequence A011762 A063571 A005589
Adjacent sequences: A048850 A048851 A048852 this_sequence A048854 A048855 A048856
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KEYWORD
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base,nonn,easy,nice
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AUTHOR
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G. L. Honaker, Jr. (honak3r(AT)gmail.com) and Patrick De Geest (pdg(AT)worldofnumbers.com).
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