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A268035 a(n) is the smallest integer m such that each of the numbers m, 2*m, 3*m, ..., n*m is the sum of two successive primes. 0
5, 12, 12, 30, 120, 1036350, 19714254, 318409146, 2281029060 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
If exactly n multiples were requested, then a(2) would be 18. - Michel Marcus, Jan 25 2016
LINKS
EXAMPLE
a(4)=30 because each of the numbers 30, 60, 90, and 120 is the sum of 2 successive prime numbers: 13+17=30, 29+31=60, 43+47=90, and 59+61=120.
MATHEMATICA
Table[m = 1; While[! AllTrue[m Range@ n, Function[m, If[PrimeQ@ #, # + NextPrime@ #, NextPrime@ # + NextPrime[#, -1]] == m &@((m - 1)/2)]], m++]; m, {n, 5}] (* Michael De Vlieger, Jan 27 2016 *)
PROG
(PARI) is(n)=precprime((n-1)/2)+nextprime(n/2)==n&&n>2; \\ from A001043
isok(m, n) = {for (k=1, n, if (! is(m*k), return (0)); ); return(1); }
a(n) = {my(j=1); while (! isok(j, n), j++); j; } \\ Michel Marcus, Jan 25 2016
CROSSREFS
Each term belongs to A001043.
Sequence in context: A265028 A259911 A259860 * A223255 A367573 A076537
KEYWORD
nonn,more
AUTHOR
David Radcliffe, Jan 24 2016
STATUS
approved

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Last modified February 26 02:39 EST 2024. Contains 370335 sequences. (Running on oeis4.)