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A155925 a(x) = if one of {4x^2 - 146x + 1373, 4x^2 - 144x + 1459, 4x^2 - 142x + 1301, 4x^2 - 140x + 1877} is prime, then pick that prime in sequence, otherwise pick zero. 1
1373, 1319, 1033, 1493, 853, 839, 593, 1093, 461, 487, 281, 821, 197, 263, 97, 677, 61, 167, 41, 661, 53, 199, 113, 773, 173, 359, 313, 1013, 421, 647, 641, 1381, 797, 1063, 1097, 1877, 1301, 1607, 2333, 1847, 1933, 2203, 2393, 3253, 2693, 3079, 3121, 4133 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

COMMENTS

The polynomials are tested in a cycle beginning with a(1 + x mod 4), i.e., when x==0 mod 4, they are tested in order t1,t2,t3,t4; when x==1 mod4, they are tested in the order t2,t3,t4,t1. If none of the polynomials are prime, a zero value is given.

LINKS

Harry J. Smith, Table of n, a(n) for n = 0..10000

EXAMPLE

n a(n)

0 1373

1 1319

2 1033

3 1493

. . .

78 14561

79 0

80 15541

. . .

4686 87170273

4687 87198407

4688 0

4689 0

4690 0

4691 0

4692 0

4693 87413191

4694 0

4695 87516677

4696 87544133

PROG

(PARI) p1(n)=4*n*n-146*n+1373 p2(n)=4*n*n-144*n+1459 p3(n)=4*n*n-142*n+1301 p4(n)=4*n*n-140*n+1877 { for (n=0, 10000, t1=p1(n); t2=p2(n); t3=p3(n); t4=p4(n); if (n%4==0, b1=t1; b2=t2; b3=t3; b4=t4; ); if (n%4==1, b1=t2; b2=t3; b3=t4; b4=t1; ); if (n%4==2, b1=t3; b2=t4; b3=t1; b4=t2; ); if (n%4==3, b1=t4; b2=t1; b3=t2; b4=t3; ); a=0; if (isprime(b1), a=b1); if (a==0 && isprime(b2), a=b2); if (a==0 && isprime(b3), a=b3); if (a==0 && isprime(b4), a=b4); print(n, " ", a); write("b155925.txt", n, " ", a); ) }

CROSSREFS

Cf. A139414.

Sequence in context: A135819 A181969 A139414 * A060981 A140125 A179915

Adjacent sequences:  A155922 A155923 A155924 * A155926 A155927 A155928

KEYWORD

nonn

AUTHOR

Harry J. Smith, Jan 31 2009

STATUS

approved

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Last modified November 18 10:18 EST 2017. Contains 294887 sequences.