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A307414 Numbers k such that A014285(k) and A007504(k) are coprime. 3
2, 3, 6, 7, 10, 11, 12, 14, 15, 18, 19, 22, 23, 24, 27, 30, 31, 32, 34, 35, 38, 39, 40, 44, 46, 47, 48, 51, 52, 55, 56, 58, 59, 60, 63, 64, 66, 67, 70, 71, 72, 74, 75, 76, 78, 79, 82, 83, 86, 87, 88, 91, 92, 94, 95, 96, 98, 99, 100, 102, 104, 106, 108, 110, 112, 114, 115, 116, 118, 119, 120, 122 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Numbers k such that A306834(k) = A014285(k).

No terms == 1 (mod 4).

Numbers k such that A309036(k)=1. - Robert Israel, Jul 09 2019

LINKS

Robert Israel, Table of n, a(n) for n = 1..10000

EXAMPLE

a(3) = 6 is a term because A007504(6) = 41 and A014285(6) = 184 are coprime.

MAPLE

N:= 1000: # for terms <= N

Primes:= map(ithprime, [$1..N]):

S1:= ListTools:-PartialSums(Primes):

S2:= ListTools:-PartialSums(zip(`*`, Primes, [$1..N])):

select(t -> igcd(S1[t], S2[t])=1, [$1..N]);

PROG

(PARI) isok(k) = my(vp=primes(k)); gcd(sum(i=1, k, vp[i]), sum(i=1, k, i*vp[i])) == 1; \\ Michel Marcus, Apr 07 2019

CROSSREFS

Cf. A007504, A014285, A306834, A309036.

Sequence in context: A263881 A208892 A085397 * A073439 A188084 A242750

Adjacent sequences:  A307411 A307412 A307413 * A307415 A307416 A307417

KEYWORD

nonn

AUTHOR

Robert Israel, Apr 07 2019

STATUS

approved

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Last modified March 7 19:13 EST 2021. Contains 341928 sequences. (Running on oeis4.)