A086711
Primes p such that A001414(p-1) = A001414(p+1), where A001414 = sum of primes dividing n (with repetition).
Original entry on oeis.org
11, 17, 31, 251, 1429, 3041, 16561, 16927, 53299, 56897, 89783, 95089, 213599, 282977, 345547, 432587, 592223, 763457, 906949, 915799, 1050449, 1058389, 1485017, 1577341, 1678399, 1780253, 1855549, 2131687, 2374289, 2658259
Offset: 1
a(3)=31 because it is prime and 30=2*3*5, 32=2^5 and 2+3+5 = 2+2+2+2+2 = 10.
A190722
Primes p such that A008472(p-1) = A008472(p+1) and is a prime.
Original entry on oeis.org
3, 45751, 149351, 171529, 223099, 434237, 678077, 706841, 1996297, 3993037, 6340457, 7199113, 7419761, 9000317, 13129271, 15052777, 17193217, 18436879, 18749881, 18998519, 23353469, 23689423, 33746663, 40985411, 41437751, 43547797, 51198097, 53773651, 56825687, 60207809, 62190113, 79778899, 81708353, 83019421
Offset: 1
For p = 45751, p-1 = 2*3*5^3*61; 2+3+5+61=71 and p+1 = 2^3*7*19*43; 2+7+19+43 = 71.
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[p:p in PrimesInInterval(3,10^8)|(&+PrimeDivisors(p-1) eq &+PrimeDivisors(p+1)) and IsPrime(&+PrimeDivisors(p-1))]; // Marius A. Burtea, Nov 14 2019
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fQ[n_] := Block[{pn = Plus @@ (First@# & /@ FactorInteger[n - 1]), pp = Plus@@ (First@# & /@ FactorInteger[n + 1])}, pn == pp && PrimeQ[pn]];
p = 2; lst = {}; While[p < 10^8, If[fQ@p, AppendTo[lst, p]; Print@p]; p =
NextPrime@p]; lst
pQ[n_]:=Module[{p1=Total[FactorInteger[n-1][[All,1]]],p2=Total[ FactorInteger[ n+1][[All,1]]]},p1==p2&&PrimeQ[p1]]; Select[ Prime[ Range[5*10^6]],pQ] (* Harvey P. Dale, Jun 18 2017 *)
A203182
Primes p such that A008472(p-1) = A008472(p+1), where A008472 = sum of distinct primes dividing n.
Original entry on oeis.org
3, 18913, 24733, 29633, 32429, 42719, 45751, 46103, 61409, 117991, 149351, 171529, 174019, 176017, 223099, 294893, 326369, 363691, 421727, 423503, 434237, 472631, 658579, 678077, 686423, 706841, 735901, 770059, 771629, 906949, 936827, 937571, 1073447, 1256029
Offset: 1
18913 is in the sequence because:
sum of the distinct prime divisors of 18912 = 2+3+197 = 202;
sum of the distinct prime divisors of 18914 = 2+7+193 = 202.
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with(numtheory):for n from 1 to 100000 do:p:=ithprime(n):p1:=p-1: p2:=p+1:t1:=ifactors(p1)[2]; t11 := sum(t1[i][1], i=1..nops(t1)):t2:=ifactors(p2)[2]; t22 := sum(t2[i][1], i=1..nops(t2)):if t11=t22 then printf(`%d, `,p):else fi:od:
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Select[Prime[Range[100000]],Total[Transpose[FactorInteger[#-1]][[1]]] == Total[Transpose[FactorInteger[#+1]][[1]]]&] (* Harvey P. Dale, Sep 22 2013 *)
Showing 1-3 of 3 results.
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