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A082073 First difference set of primes with 4k+1 form: A002144. 10
8, 4, 12, 8, 4, 12, 8, 12, 16, 8, 4, 8, 4, 24, 12, 8, 16, 8, 12, 4, 32, 4, 8, 16, 12, 8, 4, 12, 20, 4, 20, 12, 4, 20, 16, 8, 4, 8, 12, 12, 16, 8, 4, 48, 12, 20, 16, 12, 8, 16, 8, 12, 4, 24, 12, 8, 12, 4, 24, 8, 24, 24, 4, 8, 4, 24, 12, 12, 8, 24, 4, 20, 4, 48, 8, 4, 12, 24, 20, 12, 4, 8, 12 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Charles R Greathouse IV, Table of n, a(n) for n = 1..10000

FORMULA

a(n) = A002144(n+1) - A002144(n).

EXAMPLE

first and second 4k+1 primes are 5 and 13, so a(1)=13-5=8;

a(n) is divisible by 4.

MATHEMATICA

k=0; m=4; r=1; Do[s=Mod[Prime[n], m]; If[Equal[s, r], rp=ep; k=k+1; ep=Prime[n]; Print[(ep-rp)]; ], {n, 1, 1000}]

PROG

(PARI) p=5; forprime(q=7, 1e3, if(q%4==1, print1(q-p", "); p=q)) \\ Charles R Greathouse IV, May 13 2012

CROSSREFS

Cf. A002144, A002145, A082074-A082076.

Sequence in context: A194184 A194217 A239971 * A244209 A156279 A203072

Adjacent sequences:  A082070 A082071 A082072 * A082074 A082075 A082076

KEYWORD

nonn,easy

AUTHOR

Labos Elemer, Apr 07 2003

STATUS

approved

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Last modified April 23 03:26 EDT 2019. Contains 322380 sequences. (Running on oeis4.)