A056902 Numbers n where 36n^2+24n+7 is prime (sorted by absolute values with negatives before positives).

0, -1, 1, -2, 2, -4, -5, 6, 8, -9, 10, -11, -12, 12, -13, 15, -16, -18, -19, 20, -22, 22, 23, 24, -26, 26, -27, -29, -30, 36, 38, 40, -41, 41, -43, -46, -48, -50, -51, -53, -54, 54, -57, 58, 59, -61, 61, 66, -68, 69, -71, -72, 72, 73, 76, 78, -79, -81, -85, 85, 87

Offset

0,4

Comments

36m^2+24m+7=(6m+2)^2+3 which is three more than a square

Links

Table of n, a(n) for n=0..60.

Formula

36*a(n)^2+24*a(n)+7=A049423(n+1).

Example

a(3)=-2 since 36*(-2)^2+24*(-2)+7=144-48+7=103 which is prime

Crossrefs

This sequence and formula generate all but the first prime of the form k^2+3, i.e. A049423.

Sequence in context: A341467 A341468 A071528 * A089676 A334653 A230059

Adjacent sequences: A056899 A056900 A056901 * A056903 A056904 A056905

Keyword

sign

Author

Henry Bottomley, Jul 06 2000

Status

approved