The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A234851

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A234851

Indices of primes in A014692, i.e., numbers k such that prime(k)-k+1 is prime.
(history; published version)

#11 by N. J. A. Sloane at Fri Feb 19 14:36:34 EST 2021

STATUS

proposed

approved

#10 by Robert Israel at Fri Feb 19 14:04:20 EST 2021

STATUS

editing

proposed

#9 by Robert Israel at Fri Feb 19 14:04:16 EST 2021

LINKS

Robert Israel, <a href="/A234851/b234851.txt">Table of n, a(n) for n = 1..10000</a>

MAPLE

select(k -> isprime(ithprime(k)-k+1), [$1..1000]); # Robert Israel, Feb 19 2021

STATUS

approved

editing

#8 by M. F. Hasler at Sun Jan 05 16:42:16 EST 2014

STATUS

editing

approved

#7 by M. F. Hasler at Sun Jan 05 16:41:17 EST 2014

NAME

Indices of primes in A014692: Numbers , i.e., numbers k such that prime(k)-k+1 is prime.

STATUS

approved

editing

Discussion

Sun Jan 05

16:42

M. F. Hasler: to avoid the ambiguity that the 2nd part might refer to A014692 and not, as it should, to the present sequence.

#6 by M. F. Hasler at Tue Dec 31 18:18:58 EST 2013

STATUS

editing

approved

#5 by M. F. Hasler at Tue Dec 31 18:18:16 EST 2013

FORMULA

a(n) = primepiPrimePi(A234850(n)), primepi PrimePi = A000720.

PROG

(PARI) for(k=1, 999, isprime(prime(k)-k+1)&&print1(k", "))

CROSSREFS

Cf. A000040, A000720, A014692, A234695, A234850, A234852.

STATUS

approved

editing

#4 by M. F. Hasler at Tue Dec 31 17:52:47 EST 2013

STATUS

editing

approved

#3 by M. F. Hasler at Tue Dec 31 17:48:31 EST 2013

COMMENTS

Sequence A234695 lists primes in this sequence.

PROG

(PARI) for(k=1, 999, isprime(p=prime(k)-k+1)&print1(k", "))

(PARI) is_A234851(n)=isprime(prime(k)-k+1)

#2 by M. F. Hasler at Tue Dec 31 17:44:50 EST 2013

NAME

allocated for M. F. Hasler

Indices of primes in A014692: Numbers k such that prime(k)-k+1 is prime.

DATA

1, 2, 3, 5, 7, 13, 17, 21, 23, 25, 31, 41, 43, 49, 61, 71, 77, 83, 89, 103, 105, 109, 121, 129, 133, 139, 151, 161, 173, 181, 183, 185, 189, 199, 211, 213, 223, 231, 235, 241, 243, 247, 265, 271, 273, 277, 279, 281, 285, 293, 301, 303, 307, 311, 317

OFFSET

1,2

FORMULA

a(n) = primepi(A234850(n)), primepi = A000720.

PROG

(PARI) for(k=1, 999, isprime(p=prime(k)-k+1)&print1(k", "))

KEYWORD

allocated

nonn

AUTHOR

M. F. Hasler, Dec 31 2013

STATUS

approved

editing