A065838 -id:A065838 - cp's OEIS frontend

A065839 Primes found in A065838.

3, 13, 53, 859, 880571, 230836658783, 18727694659923768688081143062632211180505377, 1448985191439414787314128433365601157107793684026416650771108564122239

Offset: 1

Patrick De Geest, Nov 24 2001

In Defense of Base-Related Problems

Cf. A065828 up to A065840, A000796, A011545, A011546, A055145, A005042, A060421, A039954, A048796.

A065840 Numbers n such that the first n quaternary digits found in the base-10 expansion of Pi form a prime (when the decimal point is ignored).

Original entry on oeis.org

1, 2, 3, 5, 10, 19, 72, 115, 220, 315, 375, 12408

Offset: 1

Patrick De Geest, Nov 24 2001

In other words, take the decimal expansion of Pi, drop any digits greater than 4, omit the decimal point and look for prefixes in the resulting string which form base-4 primes.
Numbers n such that A065838(n) is prime.
The next term in the sequence, if it exists, is greater than 10000. - Nathaniel Johnston, Nov 15 2010

			E.g., the first a(5) or 10 quaternary digits of Pi are 31.12332323{4} and 3112332323{4} is the prime 880571{10}.

Cf. A065828 up to A065839, A000796, A011545, A011546, A055145, A005042, A060421, A039954, A048796.

p = First[ RealDigits[ Pi, 10, 10^5]]; p = p[[ Select[ Range[10^5], p[[ # ]] == 0 || p[[ # ]] == 1 || p[[ # ]] == 2 || p[[ # ]] == 3 & ]]]; Do[ If[ PrimeQ[ FromDigits[ Take[p, n], 4]], Print[ n]], {n, 1, 4000} ]

a(12) from Chai Wah Wu, Apr 07 2020

cp's OEIS Frontend

A065839 Primes found in A065838.

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A065840 Numbers n such that the first n quaternary digits found in the base-10 expansion of Pi form a prime (when the decimal point is ignored).

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