A366274 a(n) is the least k such that prime(n+1+k) >= prime(n)+prime(n+1).
1, 2, 2, 3, 4, 4, 4, 5, 6, 7, 8, 9, 10, 10, 10, 13, 13, 13, 14, 14, 15, 15, 16, 18, 20, 20, 19, 19, 18, 22, 24, 24, 25, 27, 27, 27, 29, 28, 29, 30, 31, 31, 33, 33, 32, 34, 37, 39, 38, 39, 40, 40, 41, 42, 42, 43, 42, 43, 43, 43
Offset: 1
Keywords
Examples
For n = 5 prime(n) = 11. prime(5) + prime(6) = 11+13=24. The 4th prime after 13 is 29 which is the next prime after 13 greater than or equal to 24. So a(5) = 4.
Links
- Patrick Butler, Table of n, a(n) for n = 1..10000
Programs
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Maple
R:= 1: pn:= 2: pn1:= 3: p:=5: m:= 4: pp:= 7: for n from 2 to 100 do pn:= pn1; pn1:= nextprime(pn1); while pp <= pn + pn1 do m:= m+1; pp:= nextprime(pp); od; R:= R, m-n-1; od: R; # Robert Israel, Oct 31 2023
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Mathematica
A366274[n_]:=PrimePi[Prime[n]+Prime[n+1]-1]-n;Array[A366274,100] (* Paolo Xausa, Dec 09 2023 *)
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PARI
a(n) = my(k=1, q=prime(n)+prime(n+1)); while(prime(n+k) < q, k++); k; \\ Michel Marcus, Oct 06 2023
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Python
m=0 #list here is a list of prime numbers A000040. def a(n): global list sum= list[n]+list[n+1] i=n+2 while True: if(list[i]>=sum): m=i break i=i+1 k = m-(n+1) return k # #calculate the terms of the sequence a(n). seq = [] for n in range(0,firstN): seq.append(a(n))
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